U.S. patent application number 14/326784 was filed with the patent office on 2015-01-08 for lead-acid battery design having versatile form factor.
The applicant listed for this patent is ENERGY POWER SYSTEMS, LLC. Invention is credited to Fabio ALBANO, Subhash DHAR, Jorge ESPINEL, William KOETTING, Michael NIELSON, Kwok TOM.
Application Number | 20150010807 14/326784 |
Document ID | / |
Family ID | 48780183 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150010807 |
Kind Code |
A1 |
DHAR; Subhash ; et
al. |
January 8, 2015 |
LEAD-ACID BATTERY DESIGN HAVING VERSATILE FORM FACTOR
Abstract
An electrochemical storage device is disclosed. The device
comprises a first electrochemical cell and a second electrochemical
cell disposed in a common casing and each comprising an anode and a
cathode. The anode of the first electrochemical cell is disposed
opposite the cathode of the second electrochemical cell. The device
further comprises a separator disposed between the anode of the
first electrochemical cell and the cathode of the second
electrochemical cell. The anode of the first electrochemical cell
and the cathode of the second electrochemical cell are electrically
insulated and in communication through an ionically conductive
medium adsorbed in the separator. The device further comprises a
common current collector disposed on the anode of the first
electrochemical cell and the cathode of the second electrochemical
cell. The first and second electrochemical cells are electrically
connected and insulated from ionic conduction.
Inventors: |
DHAR; Subhash; (Bloomfield
Hills, MI) ; KOETTING; William; (Davisburg, MI)
; NIELSON; Michael; (Royal Oak, MI) ; TOM;
Kwok; (Madison Heights, MI) ; ESPINEL; Jorge;
(Troy, MI) ; ALBANO; Fabio; (Royal Oal,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENERGY POWER SYSTEMS, LLC |
TROY |
MI |
US |
|
|
Family ID: |
48780183 |
Appl. No.: |
14/326784 |
Filed: |
July 9, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13766991 |
Feb 14, 2013 |
8808914 |
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14326784 |
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13626426 |
Sep 25, 2012 |
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13766991 |
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13350686 |
Jan 13, 2012 |
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13626426 |
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Current U.S.
Class: |
429/154 ;
429/153 |
Current CPC
Class: |
H01M 10/123 20130101;
H01M 10/122 20130101; Y02T 10/70 20130101; H01M 2/26 20130101; H01M
10/12 20130101; H01M 10/0431 20130101; H01M 10/0477 20130101; Y02E
60/10 20130101 |
Class at
Publication: |
429/154 ;
429/153 |
International
Class: |
H01M 10/12 20060101
H01M010/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2013 |
US |
PCT/US2013/021287 |
Claims
1-20. (canceled)
21. An electrochemical storage device, comprising: a first
electrochemical cell and a second electrochemical cell disposed in
a common casing and each comprising an anode and a cathode, wherein
the anode of the first electrochemical cell is disposed opposite
the cathode of the second electrochemical cell; a separator
disposed between the anode of the first electrochemical cell and
the cathode of the second electrochemical cell, wherein the anode
of the first electrochemical cell and the cathode of the second
electrochemical cell are electrically insulated and in
communication through an ionically conductive medium adsorbed in
the separator; and a common current collector disposed on the anode
of the first electrochemical cell and the cathode of the second
electrochemical cell, wherein the first and second electrochemical
cells are electrically connected and insulated from ionic
conduction and wherein the ionic separation of said first and
second electrochemical cells mitigates shunt currents.
22. The device of claim 21, wherein the current collector provides
substantially uniform current collection providing substantially
uniform current density.
23. The device of claim 21, further comprising a hydrophobic
coating disposed on the portion of the common current collector
between the anode and the cathode.
24. The device of claim 21, further comprising a physical barrier
configured to ionically insulate the first and second
electrochemical cells.
25. The device of claim 21, further comprising one positive and one
negative terminal connection.
26. The device of claim 21, further comprising an insulation frame
for disposing anodes and cathodes of two or more electrochemical
cells in substantially the same plane.
27-30. (canceled)
Description
RELATED APPLICATIONS
[0001] This application is a divisional application of application
Ser. No. 13/766,961, filed Feb. 14, 2013, which claims priority to
PCT International Application No. PCT/US2013/021287, filed on Jan.
11, 2013, and is a continuation in part of application Ser. No.
13/626,426, filed on Sep. 25, 2012, entitled "Lead-acid battery
design having versatile form factor," which is a continuation in
part of application Ser. No. 13/350,686, filed Jan. 13, 2012, also
entitled "Lead-acid battery design having versatile form factor,"
which incorporates the entire disclosure of the concurrently filed
U.S. application Ser. No. 13/350,505 entitled, "Improved Substrate
for Electrode of Electrochemical Cell." This application
incorporates, by reference, the entire contents of all the
above-listed applications.
TECHNICAL FIELD
[0002] Embodiments of the present disclosure relate generally to
electrochemical cells. More particularly, embodiments of the
present disclosure relate to a design of a lead-acid
electrochemical cell.
BACKGROUND
[0003] Lead-acid electrochemical cells have been commercially
successful as power cells for over one hundred years. For example,
lead-acid batteries are widely used for starting, lighting, and
ignition (SLI) applications in the automotive industry.
[0004] As an alternative to lead-acid batteries, nickel-metal
hydride ("Ni-MH") and lithium-ion ("Li-ion") batteries have been
used for hybrid and electric vehicle applications. Despite their
higher cost, Ni-MH and Li-ion electro-chemistries have been favored
over lead-acid electrochemistry for hybrid and electric vehicle
applications due to their higher specific energy and energy density
compared to lead-acid batteries.
[0005] While lead-acid, Ni-MH, and Li-ion batteries have each
experienced commercial success, conventionally, each of these three
types of chemistries have been limited to certain applications.
FIG. 18 shows a Ragone plot of various types of electrochemical
cells that have been used in automotive applications, depicting
their respective specific powers and specific energies compared to
other technologies.
[0006] Lead-acid battery technology is low-cost, reliable, and
relatively safe. Certain applications, such as complete or partial
electrification of vehicles and back-up power applications, require
higher specific energy than traditional SLI lead-acid batteries
deliver. As shown in Table 1, lead-acid batteries suffer from low
specific energy due to the weight of the components. Thus, there
remains a need for low-cost, reliable, and relatively safe
electrochemical cells for various applications that require high
specific energy, including certain automotive and back-up power
applications.
[0007] Lead-acid batteries have many advantages. First, they are a
low-cost technology capable of being manufactured in any part of
the world. Accordingly, production of lead-acid batteries can be
readily scaled-up. Lead-acid batteries are available in large
quantities in a variety of sizes and designs. In addition, they
deliver good high-rate performance and moderately good low- and
high-temperature performance. Lead-acid batteries are electrically
efficient, with a turnaround efficiency of 75 to 80%, provide good
"float" service (where the charge is maintained near the
full-charge level by trickle charging), and exhibit good charge
retention. Further, although lead is toxic, lead-acid battery
components are easily recycled. An extremely high percentage of
lead-acid battery components (in excess of 95%) are typically
recycled.
[0008] Lead-acid batteries suffer from certain disadvantages as
well. They offer relatively low cycle life, particularly in
deep-discharge applications. Due to the weight of the lead
components and other structural components needed to reinforce the
plates, lead-acid batteries typically have limited energy density.
If lead-acid batteries are stored for prolonged periods in a
discharged condition, sulfation of the electrodes can occur,
damaging the battery and impairing its performance. In addition,
hydrogen can be evolved in some designs.
[0009] In contrast to lead-acid batteries, Ni-MH batteries use a
metal hydride as the active negative material along with a
conventional positive electrode such as nickel hydroxide. Ni-MH
batteries feature relatively long cycle life, especially at a
relatively low depth of discharge. The specific energy and energy
density of Ni-MH batteries are higher than for lead-acid batteries.
In addition, Ni-MH batteries are manufactured in small prismatic
and cylindrical cells for a variety of applications and have been
employed extensively in hybrid electric vehicles. Larger size Ni-MH
cells have found limited use in electric vehicles.
[0010] The primary disadvantage of Ni-MH electrochemical cells is
their high cost. Li-ion batteries share this disadvantage. In
addition, improvements in energy density and specific energy of
Li-ion designs have outpaced advances in Ni-MH designs in recent
years. Thus, although nickel metal hydride batteries currently
deliver substantially more power than designs of a decade ago, the
progress of Li-ion batteries, in addition to their inherently
higher operating voltage, has made them technically more
competitive for many hybrid applications that would otherwise have
employed Ni-MH batteries.
[0011] Li-ion batteries have captured a substantial share not only
of the secondary consumer battery market but a major share of OEM
hybrid battery, vehicle, and electric vehicle applications as well.
Li-ion batteries provide high-energy density and high specific
energy, as well as long cycle life. For example, Li-ion batteries
can deliver greater than 1,000 cycles at 80% depth of
discharge.
[0012] Li-ion batteries have certain advantages. They are available
in a wide variety of shapes and sizes, and are much lighter than
other secondary batteries that have a comparable energy capacity
(both specific energy and energy density). In addition, they have
higher open circuit voltage (typically .about.3.5 V vs. 2 V for
lead-acid cells). In contrast to Ni--Cd and, to a lesser extent,
Ni-MH batteries, Li-ion batteries suffer no "memory effect," and
have much lower rates of self discharge (approximately 5% per
month) compared to Ni-MH batteries (up to 20% per month).
[0013] Li-ion batteries, however, have certain disadvantages as
well. They are expensive. Rates of charge and discharge above 1 C
at lower temperatures are challenging because lithium diffusion is
slow and it does not allow for the ions to move fast enough.
Further, Li-ion batteries use liquid electrolytes to allow for
faster diffusion rates, which results in formation of dendritic
deposits at the negative electrode, causing hard shorts and
resulting in potentially dangerous conditions. Liquid electrolytes
also form deposits (referred to as an SEI layer) at the
electrolyte/electrode interface, that can inhibit electron
transfer, indirectly causing the cell's rate capability and
capacity to diminish over time. These problems can be exacerbated
by high-charging levels and elevated temperatures. Li-ion cells may
irreversibly lose capacity if operated in a float condition. Poor
cooling and increased internal resistance cause temperatures to
increase inside the cell, further degrading battery life. Most
important, however, Li-ion batteries may suffer thermal runaway, if
overheated, overcharged, or over-discharged. This can lead to cell
rupture, exposing the active material to the atmosphere. In extreme
cases, this can cause the battery to catch fire. Deep discharge may
short-circuit the Li-ion cell, causing recharging to be unsafe.
[0014] To manage these risks, Li-ion batteries are typically
manufactured with expensive and complex power and thermal
management systems. In a typical Li-ion application for a hybrid
vehicle, two-thirds of the volume of the battery module may be
given over to collateral equipment for thermal management and power
electronics and battery management, dramatically increasing the
overall size and weight of the battery system, as well as its
cost.
[0015] In addition to the differing advantages and disadvantages of
lead-acid, Ni-MH and Li-ion batteries, the specific energy, energy
density, specific power, and power density of these three
electro-chemistries vary substantially. Typical values for systems
used in HEV-type applications are provided in Table 1 below.
TABLE-US-00001 TABLE 1 Electro-chemistry Specific Energy Energy
Density Specific Power Type (Whr/kg) (Whr/l) (W/kg) Lead-Acid.sup.1
30-50 Whr/kg 60-75 Whr/1 100-250 W/kg Nickel Metal 65-100 Whr/kg
150-250 Whr/1 250-550 W/kg Hydride (Ni-MH).sup.2 Lithium-Ion up to
131 Whr/kg 250 Whr/1 up to 2,400 W/kg (Li-ion).sup.3
.sup.1http://en.wikipedia.org/wiki/Lead_acid_battery, accessed Jan.
11, 2012. .sup.2Linden, David, ed., Handbook of Batteries, 3.sup.rd
Ed. (2002).
.sup.3http://info.a123systems.com/data-sheet-20ah-prismatic-pouch-cell,
accessed Jan. 11, 2012.
[0016] Although both Ni-MH and Li-ion battery chemistries have
claimed a substantial role in hybrid and electrical vehicles, both
chemistries are substantially more expensive than lead-acid
batteries for vehicular propulsion assist. The present inventors
believe that the embodiments of the present disclosure can
substantially improve the capacity of lead-acid batteries to
provide a viable, low-cost alternative to Ni-MH and Li-ion
electro-chemistries in all types of hybrid and electrical vehicle
applications.
[0017] In particular, certain applications have proved difficult
for Ni-MH and Li-ion batteries, such as certain automotive and
standby power applications. Standby power application requirements
have gradually been raised. The standby batteries of today have to
be truly maintenance free, have to be low-cost, have long
cycle-life, have low self-discharge, be capable of operating at
extreme temperatures, and, finally, should have high specific
energy and high specific power. Emerging smart grid applications to
improve energy efficiency require high power, long life, and lower
cost for continued growth in the market place.
[0018] Automobile manufacturers have encountered substantial
consumer resistance in launching fleets of electric vehicles and
hybrid vehicles, due to the increased cost of these vehicles
relative to conventional automobiles powered by an internal
combustion engine ("ICE"). Environmental and energy independence
concerns have exerted greater pressures on manufacturers to offer
cost-effective alternatives to internal combustion engine-powered
vehicles. Although hybrids and electric vehicles can meet that
demand, they typically rely on subsidies to defray the higher cost
of the energy storage systems.
[0019] Table 2 below compares the application of various battery
electro-chemistries and the internal combustion engine (ICE) and
their current roles in certain automotive applications. As used in
Table 2, "SLI" means starting, lighting, ignition; "HEV" means
hybrid electric vehicle; "PHEV" means plug-in hybrid electric
vehicle; "EREV" means extended range electric vehicle; and "EV"
means electric vehicle.
TABLE-US-00002 TABLE 2 Power Mild SLI Start/Stop Assist
Regeneration Hybrid HEV PHEV EREV EV Pb-Acid Ni-MH Li-ion ICE
[0020] As shown in Table 2, there remains a need for specific
applications in which partial electrification of the vehicle may
provide environmental and energy efficiency advantages, without the
same level of added costs associated with hybrid and electric
vehicles using Ni-MH and Li-ion batteries. Even more specifically,
there is a need for a low cost, energy efficient battery in the
area of start/stop automotive applications.
[0021] Specific points in the duty cycle of an internal combustion
engine entail far greater inefficiency than others. Internal
combustion engines operate efficiently only over a relatively
narrow range of crankshaft speeds. For example, when the vehicle is
idling at a stop, fuel is being consumed with no useful work being
done. Idle vehicle running time, stop/start events, power steering,
air conditioning, or other power electronics component operation
entail substantial inefficiencies in terms of fuel economy, as do
rapid acceleration events. In addition, environmental pollution
from a vehicle at these "start-stop" conditions is far worse than
from a running vehicle that is moving. The partial electrification
of the vehicle in relation to these more extreme operating
conditions has been termed a "micro" or "mild" hybrid application,
including start/stop electrification. Micro- and mild-hybrid
technologies are unable to displace as much of the power delivered
by the internal combustion engine as a full hybrid or electric
vehicle. Nonetheless, they may be able to substantially increase
fuel efficiency in a cost-effective manner without the substantial
capital expenditure associated with full hybrid or full electric
vehicle applications.
[0022] Conventional lead-acid batteries have not yet been able to
fulfill this role. Conventional lead-acid batteries have been
designed and optimized for the specific application of SLI
operation. The needs of a mild hybrid application are different. A
new process, design, and production process need to be developed
and optimized for the mild hybrid application.
[0023] One need for a mild hybrid application is low-weight
battery. Conventional lead-acid batteries are relatively heavy.
This causes the battery to have a low specific energy due to the
substantial weight of the lead components and other structural
components that are necessary to provide rigidity to the plates.
SLI lead-acid batteries typically have thinner plates, providing
increased surface area needed to produce the power necessary to
start the engine. But the grid thickness is limited to a minimum
useful thickness because of the casting process and the mechanics
of the grid hang. The minimum grid thickness is also determined on
the positive electrode by corrosion processes. Positive plates are
rarely less than 0.08'' (main outside framing wires) and 0.05'' on
the face wires because of the difficulties of casting at production
rates and, more importantly, concern over poor cycle-life issues.
These parameters limit power. Lead-acid batteries designed for
deeper discharge applications (such as motive power for forklifts)
typically have heavier plates to enable them to withstand the
deeper depth of discharge in these applications.
[0024] In addition, in typical lead-acid batteries, the active
material is usually formed as a paste that is applied to the grid
in order to form the plates as a composite material. Although the
paste adheres well to itself, it does not adhere well to the grid
materials because of paste shrinkage issues. This requires the use
of grids that are more substantial and contain additional
structural components to help support the active material, which,
in turn, puts an extra weight burden on the cell.
[0025] Further, during the manufacture of conventional lead-acid
batteries, the components are subjected to a number of mechanical
stresses. Pasting active material onto the grid can stress the
latticework of the grid. Expanded metal grids are lighter than cast
grids, yet, the formation of the expanded grid itself introduces
stress at each of the nodes of the expanded grid. These various
structural materials, being subjected to substantial mechanical
stresses during electrode pasting, handling, and cell operation,
tend to corrode more readily in the acid-oxidizing environment of
the battery after activation, especially when thin plates are used
to increase power.
[0026] For example, cast and expanded metal grids have non-uniform
stress during the life of the battery due to the molar volume
change of converting the lead metal to PbO.sub.2. This volume
change of the corrosion product puts huge stress on the grids in a
non-uniform manner because of the irregular cross-sectional shapes
of the grid wires in cast and expanded metals.
[0027] Another need for a mild hybrid application is that
rechargeable batteries should be able to be charged and discharged
with less than 0.001% energy loss at each cycle. This is a function
of the internal resistance of the design and the overvoltage
necessary to overcome it. The reaction should be energy-efficient
and should involve minimal physical changes to the battery that
might limit cycle life. Side chemical reactions that may
deteriorate the cell components, cause loss of life, create gaseous
byproducts, or loss of energy should be minimal or absent. In
addition, a rechargeable battery should desirably have high
specific energy, low resistance, and good performance over a wide
range of temperatures and be able to mitigate the structural
stresses caused by lattice expansion. When the design is optimized
for minimum resistance, the charge and discharge efficiency will
dramatically improve.
[0028] Lead-acid batteries have many of these characteristics. The
charge-discharge process is essentially highly reversible. The
lead-acid system has been extensively studied and the secondary
chemical reactions have been identified. And their detrimental
effects have been mitigated using catalyst materials or engineering
approaches. Although its energy density and specific energy are
relatively low, the lead-acid battery performs reliably over a wide
range of temperatures, with good performance and good cycle life. A
primary advantage of lead-acid batteries remains their
low-cost.
[0029] A typical lead-acid electrochemical cell uses lead dioxide
as an active material in the positive plate and metallic lead as
the active material in the negative plate. These active materials
are formed in situ. Typically, a charged positive electrode
contains PbO.sub.2. The electrolyte is sulfuric acid solution,
typically about 1.2 specific gravity or 37% acid by weight. The
basic electrode process in the positive and negative electrodes in
a typical cycle involves formation of PbO.sub.2/Pb via a
dissolution-precipitation mechanism, causing non-uniform stresses
within the positive electrode structure. The first stage in the
discharge-charge mechanism is a double-sulfate formation reaction.
Sulfuric acid in the electrolyte is consumed by discharge,
producing water as the product. Unlike many other electrochemical
systems, in lead-acid batteries the electrolyte is itself an active
material and can be capacity-limiting.
[0030] In conventional lead-acid batteries, the major starting
material is highly purified lead. Lead is used for the production
of lead oxides for conversion first into paste and ultimately into
the lead dioxide positive active material and sponge lead negative
active material. Pure lead is generally too soft to be used as a
grid material because of processing issues, except in very thick
plates or spiral-wound batteries. Lead is typically hardened by the
addition of alloying elements. Some of these alloying elements are
grain refiners and corrosion inhibitors but others may be
detrimental to grid production or battery performance generally.
One of the mitigating factors in the corrosion of lead/lead grids
is the high hydrogen over-potential for hydrogen evolution on lead.
Since most corrosion reactions are accompanied by hydrogen
evolution as the cathode reaction, reduced hydrogen evolution may
inhibit anodic corrosion as well.
[0031] The purpose of the grid is to form the support structure for
the active materials and to collect and carry the current generated
during discharge from the active material to the cell terminals.
Mechanical support can also be provided by non-metallic elements
such as polymers, ceramics, and other components. But these
components are not electrically conductive. Thus, they add weight
without contributing to the specific energy of the cell.
[0032] Lead oxide is converted into a dough-like material that can
be fixed to grids forming the plates. The process by which the
paste is integrated into the grid is called pasting. Pasting can be
a form of "ribbon" extrusion. The paste is pressed by hand trowel,
or by machine, into the grid interstices. The amount of paste
applied is regulated by the spacing of the hopper above the grid or
the type of troweling. As plates are pasted, water is forced out of
the paste.
[0033] The typical curing process for SLI lead-acid plates is
different for the positive and negative plates. Typically water is
driven off the plate in a flash dryer until the amount of water
remaining in the plate is between about 8 to 20% by weight. The
positive plate is hydro-set at low temperature (<55 C+/-5 C) and
high humidity for 24 to 72 hours. The negative plate is hydro-set
at about the same temperature and humidity for 5 to 12 hours. The
negative plate may be dried to the lower end of the 8 to 20% range
and the positive plate to the upper end of the range. More
recently, manufacturers use curing ovens where temperature and
humidity are more precisely controlled. In the conventional process
steps, the "hydro-set process" causes shrinkage of the "paste"
active material that, in turn, causes it to break away from the
grid in a non-uniform manner. The grid metal that is exposed is
corroded preferentially and, since it is not in contact locally
with the active material, results in increased resistance as well
as formation, and life issues.
[0034] A simple cell consists of one positive and one negative
plate, with one separator positioned between them. Most practical
lead-acid electrochemical cells contain between 3 and 30 plates
with separators between them. Leaf separators are typically used,
although envelope separators may be used as well. The separator
electrically insulates each plate from its nearest
counter-electrode but must be porous enough to allow acid transport
in or out of the plates.
[0035] A variety of different processes are used to seal battery
cases and covers together. Enclosed cells are necessary to minimize
safety hazards associated with the acidic electrolyte, potentially
explosive gases produced on overcharge, and electric shock. Most
SLI batteries are sealed with fusion of the case and cover,
although some deep-cycling batteries are heat sealed. A wide
variety of glues, clamps, and fasteners are also well-known in the
art.
[0036] Typically, formation is initiated after the battery has been
completely assembled. Formation activates the active materials.
Batteries are then tested, packaged, and shipped.
[0037] A number of trade-offs must be considered in optimizing
lead-acid batteries for various standby power and transportation
uses. High-power density requires that the initial resistance of
the battery be minimal. High-power and energy densities also
require the plates and separators be highly porous. High cycle
life, in contrast, requires optimized separators, shallow depth of
discharge, and the presence of alloying elements in the substrate
grids to reduce corrosion. Low-cost, in further contrast, requires
both minimum fixed and variable costs, high-speed automated
processing, and that no premium materials be used for the grid,
paste, separator, or other cell and battery components.
[0038] A number of improvements have been made in the basic design
of lead-acid electrochemical cells. Many of these have involved
improvements in the characteristics of the substrate, the active
material, as well as the bus bars or collector elements. For
example, a variety of fibers or metals have been added to or
embedded in the substrate material to help strengthen it. The
active material has been strengthened with a variety of materials,
including synthetic fibers and other additions. Particularly with
respect to lead-acid batteries, these various approaches represent
a trade-off between durability, capacity, and specific energy. The
addition of various non-conductive strengthening elements helps
strengthen the supporting grid but replaces conductive substrate
and active material with non-conductive components.
[0039] In order to reduce the weight of the lead-acid
electrochemical cells relative to their specific energy, various
improvements have been disclosed. One approach has been to coat a
light-weight, high-tensile strength fiber with sufficient lead to
make a composite wire that could be used to support the grid of the
electrode. Robertson, U.S. Pat. No. 275,859 discloses an apparatus
for extrusion of lead onto a core material for use as a telegraph
cable. Barnes, U.S. Pat. No. 3,808,040 discloses strengthening a
conductive latticework to serve as a grid element by depositing
strips of synthetic resin. Specifically, Barnes '040 patent
discloses a lead-coated glass fiber. These approaches, however,
have been unable to produce a material with sufficient properties
of high-corrosion resistance and high-tensile strength to be able
to fabricate a commercially viable lead-acid battery that can
survive chemical attack from the electrolyte.
[0040] Blayner, et al., have disclosed further improvements in the
composition of the substrate to reduce the weight of the electrodes
and to increase the proportion of conductive material. Blayner,
U.S. Pat. Nos. 5,010,637 and 4,658,623. Blayner discloses a method
and apparatus for coating a fiber with an extruded,
corrosion-resistant metal. Blayner discloses a variety of core
materials that can include high-tensile strength fibrous material,
such as an optical glass fiber, or highly-conductive metal wire.
Similarly, Blayner discloses that the extruded, corrosion-resistant
metal can be any of a number of metals such as lead, zinc, or
nickel.
[0041] Blayner discloses that a corrosion-resistant metal is
extruded through die. The core material is drawn through the die as
the metal is extruded onto the core material. Continuous lengths of
metal wire or fiber are coated with a uniform layer of extruded,
corrosion-resistant metal. The wire is then used to weave a screen
that acts as a substrate for the active material. There are no
fusion points at the intersections of the woven wires. The
electrode may be constructed using such a screen as a grid with the
active material being applied onto the grid. Rechargeable lead-acid
electrochemical cells are constructed using pairs of
electrodes.
[0042] Blayner discloses further improvements regarding the grain
structure of the metal coating on the core material. In particular,
Blayner discloses that the extruded corrosion-resistant metal has a
longitudinally-oriented grain structure and uniform grain size.
U.S. Pat. Nos. 5,925,470 and 6,027,822.
[0043] Fang, et al., disclose in their paper, Effect of Gap Size on
Coating Extrusion of Pb-GF Composite Wire by Theoretical
Calculation and Experimental Investigation, J. Mater. Sci.
Technol., Vol. 21, No. 5 (2005), optimizing the gap in extruding
lead-coated glass fiber. Although Blayner does not disclose the
relationship between gap size and extrusion of the lead coated
composite wire, Fang characterizes gap size as a key parameter for
the continuous coating extrusion process. Fang reports that a gap
between 0.12 mm and 0.24 mm is necessary, with a gap of 0.18 mm
being optimal. Fang further reports that continuous fiber composite
wire can enhance load and improve energy utilization.
[0044] The present inventors have found that, despite improvements
in lead-acid electrochemical cells for automotive applications,
prior known lead-acid batteries have not been able to achieve the
same performance as Li-ion or Ni-MH cells for similar applications.
There remains a need, therefore, for further improvements in the
design and composition of lead-acid electrochemical cells to meet
the specialized needs of the automotive and standby power markets.
Specifically, there remains a need for a reliable replacement for
lithium-ion electrochemical cells in certain applications that do
not entail the same safety concerns raised by Li-ion
electrochemical cells. Similarly, there remains a need for a
reliable replacement for Ni-MH and Li-ion electrochemical cells
with the added benefits of low-cost and reliability of lead-acid
electrochemical cells. In addition, there remains a need for
substantial improvement in battery production capacity to meet the
growing needs of the automotive and standby power segments.
[0045] The United States Department of Energy (USDOE) has issued
Corporate Average Fuel Efficiency (CAFE) guidelines for automotive
fleets. Previously, SUVs and light trucks were excluded from the
CAFE averages for motor vehicles. More recently, however,
integrated guidelines have emerged specifying fuel efficiency
standards for passenger vehicles, light trucks, and SUVs. These
guidelines require an average fuel efficiency of 31.4 miles per
gallon by 2016.
http://www.epa.gov/oms/climate/regulations/420r10009.pdf.
[0046] Anticipated improvements in internal combustion engine
technology do not appear to be able to reach this goal. Similarly,
the manufacturing capacity for pure hybrids and pure electric
vehicles does not appear sufficient to be able to reach this goal.
Thus, it is anticipated that some combination of micro-hybrids or
mild hybrids, in which electrochemical cells provide some of the
power for either stop/start or certain acceleration applications,
will be necessary in order to meet the CAFE standards.
[0047] Lead-acid battery systems may provide a reliable replacement
for Li-ion or Ni-MH batteries in these applications, without the
substantial safety concerns associated with Li-ion electrochemistry
and the increased cost associated with both Li-ion and Ni-MH
batteries.
[0048] Further, the improved batteries of the present invention may
be combined in hybrid systems with other types of electrochemical
cells to provide electric power that is tailored to the unique
automotive application. For example, a lead-acid battery of the
present invention which features high-power can be combined with a
Lithium-ion ("Li-ion") or Nickel metal hydride ("Ni-MH")
electrochemical cell offering high energy, to provide a composite
battery system tailored to the needs of the particular automotive
standby or stationary power application, while reducing the
relative sizes of each component.
SUMMARY
[0049] An aspect of the present disclosure includes an
electrochemical cell having an electrode assembly, wherein the
electrode assembly may include a plurality of electrode plates.
Each electrode plate may include a current collector having a first
portion and a second portion, and wherein each first and second
portion may have a first surface and a second surface opposing the
first surface. The first and second surfaces of the first portion
may include a positively charged active material, and the first and
second surfaces of the second portion may include a negatively
charged active material. The plurality of electrode plates may
include at least three electrode plates, such that the
electrochemical cell may be arranged with a first portion of one
plate of the at least three electrode plates electrochemically
connected to a second portion of a second plate of the at least
three electrode plates, and a first portion of the second plate of
the at least three electrode plates electrochemically may be
connected to a second portion of a third plate of the at least
three electrode plates.
[0050] In various embodiments, the electrochemical cell may include
the following features, either alone or in combination: each
electrode plate may include a plurality of electrode connectors
connecting the first portion to the second portion; each electrode
plate may include shunt current mitigating means; the current
collector may include a uniform current density; a first separator
may be attached to the first surface of the first portion and a
second separator may be attached to the first surface of the second
portion; a plurality of electrode assemblies may be stacked in
series for building voltage; an insulator may be connected to the
top electrode plate, and the insulator may include at least one
slit therein with an electrode plate extending there through; the
electrochemical cell may be a lead-acid electrochemical cell; the
electrode assembly may be connected to tabs; at least two electrode
assemblies may be stacked in parallel for building capacity; there
may be at least one power bus assembly including at least one bolt
for building capacity; at least two of the electrode plates may be
electrochemically connected at a ninety degree angle relative to
one another; and the electrochemical cell may include a
cross-sectional shaped selected from one of circular, rectangular,
square, L-shaped, or U-shaped.
[0051] In some embodiments, an electrochemical storage device
comprises a plurality of layer electrodes, wherein each layer
electrode includes a first charged sector and a second charged
sector, wherein the second charged sector is charged oppositely
compared to the first charged sector, and wherein the plurality of
layer electrodes are assembled with respect to each other such that
the first charged sector of a first plate of the plurality of layer
electrodes is laid below the second charged sector of a second
plate of the plurality of layer electrodes located immediately
above the first plate, wherein the charges of the first charged
sectors of the first and second plates have a first sign and the
charges of the second charged sectors of the first and second
plates have a second sign that is opposite the first sign; a
separator sector located, and enabling ionic charge exchange
between the first charged sector of the first plate and the second
charged sector of the second plate.
[0052] In some embodiments, the second charged sector of the first
plate is laid below the first charged sector of the second plate,
the electrochemical device further comprising an insulator sector
located, and preventing ionic or conductive charge exchange,
between the second charged sector of the first plate and the first
charged sector of the second plate. In some embodiments, each of
the plurality of the layer electrodes in circular.
[0053] In some embodiments, each sector has a semi-circle shape
sized to about half of the corresponding layer electrode. In some
embodiments, each plate of the plurality of layer electrodes
further comprises a frame which houses the first charged sector and
the second charged sector of the corresponding plate. In some
embodiments, the electrochemical storage device further comprises a
first cap and a second cap for encasing the plurality of layer
electrodes. In some embodiments, the electrochemical storage device
further comprises a conductive substrate for providing a conductive
connection between the first charge sector and the second charged
sector.
[0054] In some embodiments, each of the plurality of the layer
electrodes has a rectangular shape. In some embodiments, each
sector has a half-rectangle shape sized to about half of the
corresponding layer electrode.
[0055] In some embodiments, an electrochemical storage device
comprises a first electrochemical cell and a second electrochemical
cell disposed in a common casing and each comprising an anode and a
cathode, wherein the anode of the first electrochemical cell is
disposed opposite the cathode of the second electrochemical cell; a
separator disposed between the anode of the first electrochemical
cell and the cathode of the second electrochemical cell, wherein he
anode of the first electrochemical cell and the cathode of the
second electrochemical cell are electrically insulated and in
communication through an ionically conductive medium adsorbed in
the separator; a common current collector disposed on the anode of
the first electrochemical cell and the cathode of the second
electrochemical cell, wherein the first and second electrochemical
cells are electrically connected and insulated from ionic
conduction and wherein the ionic separation of said first and
second electrochemical cells mitigates shunt currents.
[0056] In some embodiments, the device further comprises said
current collector providing substantially uniform current
collection granting uniform current density. In some embodiments,
the device further comprises a hydrophobic coating disposed on the
portion of the common current collector between said anode and said
cathode. In some embodiments, the device further comprises a
physical barrier to ionically insulate said first and second
electrochemical cells. In some embodiments, the device further
comprises one positive and one negative terminal connection. In
some embodiments, the device further comprises an insulation frame
for disposing anodes and cathodes of two or more electrochemical
cells in substantially the same plane.
[0057] In some embodiments, a spiral wound electrochemical storage
device comprises a cylindrical cell pack including a cell stack,
wherein the cell stack includes a cell strip rolled from a flat
configuration to form the cylindrical cell stack; and a cylindrical
case for housing the cylindrical cell pack. In some embodiments,
the cell stack is a first cell stack of a plurality of cell stacks
included in the cylindrical cell pack, and wherein the plurality of
cell stacks are connected in series. In some embodiments, the cell
stack includes a plurality of strips including a positive half
electrode strip, a negative half electrode strip, and a separator
half part strip, and wherein the plurality of half strips are laid
over each other to form the cell stack. Some embodiments further
comprise a center mandrel, wherein the cell stack is rolled around
the center mandrel.
[0058] In some embodiments, a method of manufacturing a spiral
wound electrochemical storage device comprises providing a flat
cell strip; rolling the flat cell strip in the form of a
cylindrical cell stack; connecting the cylindrical cell stack to a
positive terminal and to a negative terminal; and inserting the
cylindrical cell stack in a cylindrical case. In some embodiments,
the flat cell strip is a first cell strip of a plurality of cell
strips, and the method further comprises laying the plurality of
cell strips flat to form a plurality of cell stacks; connecting the
plurality of cell stacks in series; and rolling the plurality of
cell stacks to form the cylindrical cell pack. In some embodiments,
the cell stack includes a plurality of strips including a positive
half electrode strip, a negative half electrode strip, and a
separator half part strip, and the method comprises laying the
plurality of half strips over each other to form the cell stack.
Some embodiments comprise providing a center mandrel; and rolling
the flat cell strip around the center mandrel to form the
cylindrical cell stack.
[0059] In some embodiments, an electrochemical storage device
comprises an electrochemical cell pack, wherein the electrochemical
cell pack terminates in a tab; and a power bus formed from a sheet
of metal, wherein the power bus electrically connects the tab to a
device terminal, and wherein the power bus is attached to the tab
by welding the sheet of metal to the tab. In some embodiments, the
sheet of metal is attached to the tab by ultrasonic welding. In
some embodiments, the sheet of metal is folded to form a top
surface, a front surface, and a back surface, and wherein the top
surface is electrically connected to the device terminal and the
front surface is welded around the tab. In some embodiments, the
tab is one tab of a plurality of tabs and wherein the power bus is
attached to each of the plurality of tabs by welding the sheet of
metal to the corresponding tab. In some embodiments, the power bus
has a varying resistivity at different points to provide balanced
total resistances between each of the plurality of tabs and the
device terminal. In some embodiments, the power bus has a varying
resistivity at different points by having a varying thickness at
different points. In some embodiments, the power bus has a varying
resistivity at different points by forming holes at some locations
of the power bus.
[0060] In some embodiments, a method of manufacturing
electrochemical storage device comprises providing an
electrochemical cell pack, wherein the electrochemical cell pack
terminates in a tab; providing a power bus section which includes a
flat sheet of metal; folding and welding the flat sheet of metal to
the tab; and electrically connecting the power bus to a device
terminal. In some embodiments, welding the flat sheet of metal to
the tab includes ultrasonic welding of the sheet of metal to the
tab. In some embodiments, folding the flat sheet of metal includes
forming a top surface, a front surface, and a back surface, wherein
the top surface is electrically connected to the device terminal
and the front surface is welded around the tab. In some
embodiments, the tab is one tab of a plurality of tabs, wherein the
power bus is attached to each of the plurality of tabs by welding
the sheet of metal to the corresponding tab. Some embodiments
further comprise providing balanced total resistances between each
of the plurality of tabs and the device terminal by varying
resistivity of the power bus at different points. In some
embodiments, varying the resistivity of the power bus at different
points includes varying thickness of the power bus at different
points. In some embodiments, varying the resistivity of the power
bus at different points includes forming holes at some locations of
the power bus.
[0061] In some embodiments, an electrochemical storage device
comprises a plurality of layer electrodes, wherein each layer
electrode includes a first charged sector and a second charged
sector, wherein the second charged sector is charged oppositely
compared to the first charged sector, and wherein the plurality of
layer electrodes are assembled with respect to each other such that
the first charged sector of a first plate of the plurality of layer
electrodes is laid below the second charged sector of a second
plate of the plurality of layer electrodes located immediately
above the first plate, wherein the charges of the first charged
sectors of the first and second plates have a first sign and the
charges of the second charged sectors of the first and second
plates have a second sign that is opposite the first sign; a
separator sector located, and enabling ionic charge exchange
between the first charged sector of the first plate and the second
charged sector of the second plate.
[0062] In some embodiments, the second charged sector of the first
plate is laid below the first charged sector of the second plate,
the electrochemical device further comprising an insulator sector
located, and preventing ionic or conductive charge exchange,
between the second charged sector of the first plate and the first
charged sector of the second plate. In some embodiments, each of
the plurality of the layer electrodes in circular. In some
embodiments, each sector has a semi-circle shape sized to about
half of the corresponding layer electrode. In some embodiments,
each plate of the plurality of layer electrodes further comprises a
frame which houses the first charged sector and the second charged
sector of the corresponding plate.
[0063] Some embodiments further comprise a first cap and a second
cap for encasing the plurality of layer electrodes. Some
embodiments further comprise a conductive substrate for providing a
conductive connection between the first charge sector and the
second charged sector. In some embodiments, each of the plurality
of the layer electrodes has a rectangular shape. In some
embodiments, each sector has a half-rectangle shape sized to about
half of the corresponding layer electrode.
[0064] In some embodiments, an electrochemical storage device
comprises a first electrochemical cell and a second electrochemical
cell disposed in a common casing and each comprising an anode and a
cathode, wherein the anode of the first electrochemical cell is
disposed opposite the cathode of the second electrochemical cell; a
separator disposed between the anode of the first electrochemical
cell and the cathode of the second electrochemical cell, wherein he
anode of the first electrochemical cell and the cathode of the
second electrochemical cell are electrically insulated and in
communication through an ionically conductive medium adsorbed in
the separator; a common current collector disposed on the anode of
the first electrochemical cell and the cathode of the second
electrochemical cell, wherein the first and second electrochemical
cells are electrically connected and insulated from ionic
conduction and wherein the ionic separation of said first and
second electrochemical cells mitigates shunt currents.
[0065] In some embodiments, the current collector provides
substantially uniform current collection granting uniform current
density. Some embodiments further comprise a hydrophobic coating
disposed on the portion of the common current collector between the
anode and the cathode. Some embodiments further comprise a physical
barrier configured to ionically insulate the first and second
electrochemical cells. Some embodiments further comprise one
positive and one negative terminal connection. Some embodiments
further comprise an insulation frame for disposing anodes and
cathodes of two or more electrochemical cells in substantially the
same plane. In some embodiments, the conductive substrate is made
of amorphous material. In some embodiments, the conductive
substrate is a wire mesh that includes elongated straight wires
extending in a direction pointing from the first sector to the
second sector. In some embodiments, each of rectangular plurality
of the layer electrodes has a width in a direction that points from
the first sector to the second sector and a length that is
perpendicular to, and larger than, the width. Some embodiments
further comprise an internal section, a base and an insert, wherein
the internal section includes the plurality of layer electrodes and
the separator, and wherein the base is configured to form an
external surface of the electrochemical device, and wherein the
insert is configured for insertion between the base and the
internal section and is further configured to add to a rigidity of
the base.
[0066] Additional objects and advantages of the disclosure will be
set forth in part in the description which follows, and in part
will be apparent from the description, or may be learned by
practice of the disclosure. The objects and advantages of the
disclosure will be realized and attained by means of the elements
and combinations particularly pointed out in the appended
claims.
[0067] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
[0068] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate one embodiments
of the disclosure and together with the description, serve to
explain the principles of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] FIG. 1 is a schematic isometric view of a portion of a
lead-acid electrochemical cell showing a plurality of electrode
assemblies connected in a spiral configuration according to an
embodiment of the present disclosure.
[0070] FIG. 2A is a schematic isometric view of a portion of an
electrode assembly according to an embodiment of the present
disclosure.
[0071] FIG. 2B is an exploded isometric view of a portion of the
electrode assembly of FIG. 2A.
[0072] FIGS. 3A and 3B are side views of the electrode assembly of
FIG. 2A.
[0073] FIG. 4A is a schematic top view of an electrode plate of the
electrode assembly of FIG. 2A.
[0074] FIG. 4B is an exploded isometric view of the electrode plate
of FIG. 4A with accompanying separator and pasting papers.
[0075] FIG. 5 is a schematic top view of an alternative embodiment
of an electrode plate of the electrode assembly of FIG. 2A
depicting the current collector.
[0076] FIG. 6 is an exploded isometric view of a lead-acid
electrochemical cell module and package according to an embodiment
of the present disclosure.
[0077] FIG. 7 is a schematic isometric view of a plurality of
electrode assemblies connected in a spiral configuration according
to another embodiment of the present disclosure.
[0078] FIG. 8 is an exploded isometric view of a portion of an
electrode assembly of the lead-acid electrochemical cell of FIG.
7.
[0079] FIG. 9 is an exploded isometric view of a portion of a
lead-acid electrochemical cell module according to another
embodiment of the present disclosure.
[0080] FIG. 10 is a schematic isometric view of two stacked
lead-acid electrochemical cell modules of FIG. 9 connected in
series.
[0081] FIG. 11 is a schematic isometric view of an electrode plate
according to another embodiment of the present disclosure.
[0082] FIG. 12 is an exploded isometric view of a partial electrode
assembly according to another embodiment of the present
disclosure.
[0083] FIG. 13 is a schematic isometric view of a portion of a
lead-acid electrochemical cell with a plurality of electrode
assemblies in a stacked configuration according to another
embodiment of the present disclosure.
[0084] FIG. 14A is a schematic isometric view of the lead-acid
electrochemical cell of FIG. 13 connected to a power bus.
[0085] FIG. 14B is an exploded isometric view of the power bus of
FIG. 14A.
[0086] FIGS. 15A-15D show electro-chemical cells including welded
power buses according to some embodiments.
[0087] FIGS. 15E-15H show depicts lid and base inserts according to
some embodiments.
[0088] FIG. 16 is an exploded isometric view of a partial lead-acid
electrochemical cell module, power bus, and package according to
another embodiment of the present disclosure.
[0089] FIG. 17 is a schematic isometric view of a lead-acid
electrochemical cell with a plurality of electrode assemblies in a
stacked configuration according to another embodiment of the
present disclosure.
[0090] FIG. 18 shows a Ragone plot of various types of
electrochemical cells.
[0091] FIGS. 19A-19F shows a circular plate module in accordance
with some embodiments of the present disclosure.
[0092] FIG. 20 shows an electrode assembly of a battery module
according to some embodiments.
[0093] FIG. 21 shows two circular frames in accordance with some
embodiments.
[0094] FIG. 22 shows the structure of a circular frame in
accordance with some other embodiments.
[0095] FIG. 23 shows a circular module cover in accordance with one
embodiment.
[0096] FIG. 24 shows the behavior of calculated capacity of
circular plate modules as a function of the diameter of the
circular plates, in accordance with some embodiments.
[0097] FIG. 25 shows a battery shaped as a rectangular box in
accordance with some embodiments.
[0098] FIGS. 26A-26H show a battery having a rectangular form
factor in accordance with some embodiments.
[0099] FIGS. 27A and 27B show a rectangular battery having a 192V
voltage configuration according to one embodiment.
[0100] FIGS. 28A-28D show a battery having a circular sector
electrode design according to some embodiments.
[0101] FIGS. 29A-29E show spiral wound modules according to various
embodiments.
[0102] FIG. 30A shows a cross section of a spiral wound module
according to some embodiments.
[0103] FIG. 30B shows a path of the electron flow through a cell
pack according to some embodiments.
[0104] FIG. 31 shows a cross section of a spiral wound module
according to some embodiments.
DETAILED DESCRIPTION
[0105] The following detailed description refers to the
accompanying drawings. Wherever possible, the same reference
numbers may be used in the drawings and the following description
to refer to the same or similar parts. Also, similarly-named
elements may perform similar functions and may be similarly
designed. Numerous details are set forth to provide an
understanding of the embodiments described herein. In some cases,
the embodiments may be practiced without these details. In other
instances, well-known techniques and/or components may not be
described in detail to avoid obscuring described embodiments. While
several exemplary embodiments and features are described herein,
modifications, adaptations, and other implementations are possible,
without departing from the spirit and scope of the invention.
Accordingly, the following detailed description does not limit the
invention. Instead, the proper scope of the invention is defined by
the appended claims.
[0106] Embodiments of the present disclosure generally relate to a
design of a lead-acid electrochemical cell. Lead-acid
electrochemical cells typically are in the form of stacked plates
with separators between the plates. Accordingly, embodiments of the
present disclosure relate to improved stacking of electrode plates
in a variety of form factors. The improved stacking and variety of
form factors of the lead-acid electrochemical cell design may
enable lead-acid electrochemical cells to be used as part of
lead-acid batteries, which, in turn, may be used in automobiles to
aid in increasing fuel efficiency.
[0107] More specifically, embodiments of the present disclosure may
include improvements to the design of a lead-acid electrochemical
cell which may include improvements to the orientation of electrode
plates as well as improvements for mitigating shunt currents. The
improvements may result in a lead-acid electrochemical cell that
may have a higher voltage while maintaining a lower weight and
size. Alternatively, it also enables production of cells having
higher capacity at the same relative voltage.
[0108] Embodiments of the present disclosure may allow for the use
of lead-acid batteries in micro and mild-hybrid applications of
vehicles, either alone or in combination with Ni-MH or Li-ion
batteries. Some embodiments use other electrochemical batteries
having a specific energy above 50 Wh/kg and a specific power above
500 W/kg. It should be emphasized, however, that embodiments of the
present disclosure are not limited to transportation and automotive
applications. Embodiments of the present disclosure may be of use
in any area known to those skilled in the art where use of
lead-acid batteries is desired, such as stationary power uses and
energy storage systems for back-up power situations. Further, the
present inventors intend that the elements or components of the
various embodiments disclosed herein may be used together with
other elements or components of other embodiments.
[0109] FIG. 1 depicts a lead-acid electrochemical cell 10 according
to a first embodiment of the present disclosure. The lead-acid
electrochemical cell 10 may include a plurality of electrode
assemblies 12. Each electrode assembly 12 may include a plurality
of electrode plates positioned in electrochemical contact with each
other. The electrode assemblies 12 may be connected in a spiral
configuration to build voltage within the lead-acid electrochemical
cell. In particular, the spiral configuration may enable a
lead-acid electrochemical cell to build voltage while maintaining
constant capacity. The number of electrode assemblies that make up
the spiral configuration, as well as the configuration of each
electrode assembly, may vary depending on the desired shape and
desired voltage of the lead-acid electrochemical cell.
[0110] In addition, as shown in FIG. 1, the spiral configuration
may have an opening 32 formed in the center of the stacked
electrode assemblies, by virtue of the shapes of electrode
assemblies 12. The central opening 32 may extend through the entire
spiral configuration, forming a central bore allows for the main
positive and negative leads to run through each electrode assembly
12 and be connected to the top of the spiral configuration.
[0111] Each electrode assembly 12 in the lead-acid electrochemical
cell may be separated by an insulator 14 (FIG. 2B). The insulator
may be the cross-sectional shape of the electrode assembly and may
include a radial slit 15. For example, in the embodiment of FIG. 1,
the cross-sectional shape of each electrode assembly 12 may be
semi-circular. Accordingly, the insulator 14 may include a circular
shape and a slit 15 along a radius. As shown in FIG. 2B, the
insulator 14 may further include a bottom surface and a top
surface. Further, each electrode assembly 12 may include multiple
electrode plates 24 with a top plate 24D in contact with both the
top and bottom surfaces of insulator 14. For example, as shown in
FIG. 2B, the top plate 24D of one electrode assembly may include a
first portion in contact with the bottom surface of the insulator,
and a second portion in contact with the top surface of the
insulator. The spiral configuration of the lead-acid
electrochemical cell may be achieved by connecting the second
portion of the top electrode plate 24D in one electrode assembly 12
to the first portion of a bottom electrode plate 24A in another
electrode assembly 12.
[0112] FIG. 2A and FIG. 2B of the present disclosure depict
schematic views of an electrode assembly 12 of the lead-acid
electrochemical cell of FIG. 1. As shown in FIG. 2B, the electrode
assembly may include four electrode plates 24A-D. Each electrode
plate may be in the shape of half of a semi-circular section, as
shown in FIG. 4A and FIG. 4B.
[0113] As shown in FIG. 4A, each electrode plate 24 may include a
first portion 28 and a second portion 30. The first and second
portions 28 and 30 may be connected by a plurality of electrode
connectors 26. Each portion may include a substrate, which may be a
current collector (not shown). As described above, the electrode
substrate may be of the type disclosed in U.S. application Ser. No.
13/350,505 for Improved Substrate for Electrode of Electrochemical
Cell, filed concurrently herewith by Subhash Dhar, et al., the
entire disclosure of which is incorporated herein by reference.
[0114] Thus, the substrate may include a grid-like structure formed
of conductive material, with spaces there between for supporting
active material. Accordingly, the substrate may include a sheet of
material having aligned dimple-like spaces or a plurality of
through-holes in linear patterns. Alternatively, the substrate may
include a plurality of pieces of material, such as wires, woven
together to form a mesh. In a further embodiment, the substrate may
include an expanded sheet of material with holes there through. The
substrate may include material that may result in an increased
adhesion between the substrate and the active material, as well as
increased surface conductivity and reduced corrosion of the
electrode plate.
[0115] As shown in FIGS. 4A and 4B, the positive and negative
portions of each electrode plate are depicted as 90.degree.
sections. It will be apparent to persons of ordinary skill in the
art that sections of various alternative geometries may be
employed, without departing from the scope or spirit of the
invention as claimed. For example, sections could be 30.degree., or
45.degree., 60.degree., or any other appropriate geometry. If
90.degree. sections are employed, four pairs of positive and
negative electrodes may comprise each layer; if 60.degree. sections
are employed, 6 pairs; if 45.degree. sections are used, 8 pairs; if
30.degree. sections are used, 12 pairs; and so forth. Persons of
ordinary skill will appreciate that, as the number of sections per
layer increases, the area of the active material in each section
decreases, proportionately, at a constant radius. This decrease can
be offset by increasing the radius of the electrode to provide more
active material surface area as the number of sections
increases.
[0116] The substrate may further be formed such that a relatively
constant current density may be maintained throughout each
electrode plate. For example, in the first embodiment of the
electrode plate of FIG. 4A, the electrode plate 24 may include a
substantially semi-circular shape. Accordingly, the substrate of
the electrode plate 24 may include a substantially semi-circular
shape as well. Constant current density throughout the substrate
may be achieved by spacing the current collector elements of the
substrate closer together in the radial direction at the outer
radius of the electrode plate than at the inner diameters, and
farther apart at the inner radial extent of the plate, as shown in
FIG. 5.
[0117] The active material may be placed onto each portion of the
substrate such that a pseudo bi-polar electrode plate may be
formed. The pseudo bi-polar design may be accomplished by disposing
both positive and negative active materials in alternating fields
on a common substrate. In one embodiment shown in FIG. 4A, for
example, the pseudo bi-polar design may include placing positive
active material onto the first portion 28 of the substrate; and
placing negative active material onto the second portion 30 of the
substrate. This pseudo bi-polar design may offer lower resistance
and higher power of the lead-acid electrochemical cell. Further, it
may enable the lead-acid electrochemical cell to operate at a lower
temperature, which may reduce the need for collateral cooling
equipment. As shown in FIG. 4A and FIG. 4B, the first portion 28 of
each electrode plate 24 may be positive 16, and the second portion
30 of each electrode plate 24 may be negative 20, with the
electrode connectors 26 between the negative and positive regions
of the electrode plate.
[0118] Each positive portion 16 and negative portion 20 of each
electrode plate may further include a top surface and a bottom
surface. As shown in FIG. 4B, a thin layer of pasting paper 22 may
be disposed on the top and bottom surfaces of each portion of the
electrode plate. Additionally, a separator 18 may be disposed
adjacent the pasting paper on the bottom surface of each
portion.
[0119] As previously disclosed, each electrode assembly 12 may
include four electrode plates 24A-D as shown in FIGS. 2A and 2B.
The electrode assembly 12 may be formed by stacking each plate 24
at a ninety degree angle relative to one another such that a
positive portion 16 of one plate may be connected to a negative
portion 20 of another plate. In one embodiment, for example, a
first electrode plate 24A having a positive portion 16 and a
negative portion 20 may be the bottom plate of the electrode
assembly. A second electrode plate 24B having a positive portion 16
and a negative portion 20 may then be stacked onto the first
electrode plate 24A. This may be accomplished by turning the second
electrode plate 24B ninety degrees relative to the first electrode
plate and placing the positive portion 16 of the second plate 24B
on top of the negative portion 20 of the first plate 24A (FIG. 2B).
A third electrode plate 24C having a positive portion 16 and a
negative portion 20 may be stacked upon the second plate 24B in the
same manner as previously discussed; and a fourth electrode plate
24D may then be stacked upon the third electrode plate 24C. The
fourth electrode plate 24D may be the top electrode plate of the
electrode assembly 12 (FIG. 2B).
[0120] Upon placement of the fourth electrode plate 24D, insulator
14 may be placed on the electrode assembly. As previously
discussed, and shown in FIG. 2B, the positive portion 16 of the
fourth, i.e., top electrode plate 24D may be connected to the
negative portion 20 of the third electrode plate 24C. The insulator
14, including the slit 15, may be placed on the electrode assembly
such that the top of positive portion 16 of the fourth plate 24D
may be in contact with the bottom surface of the insulator 14, and
the bottom of the negative portion 20 of the fourth plate 24D may
be in contact with the top surface of the insulator 14.
Accordingly, the negative portion 20 of the fourth plate 24D may be
stacked with a free, positive portion 16 of a first plate 24A of
another electrode assembly 12, which may thereby form the spiral
configuration of the lead-acid electrochemical cell shown in FIG.
1.
[0121] Alternatively, the electrode assembly may be formed such
that the free portion of the fourth plate 24D is a positive portion
and the free portion of the first plate 24A is a negative portion.
In addition, the free portion of the fourth plate 24D of the top
electrode assembly in the spiral configuration may be connected to
a single portion plate in order to complete the circuit. In an
alternative embodiment, the top plate 24D of the top electrode
assembly may only be a single portion plate, thereby completing the
circuit with the connection to the third plate 24D.
[0122] In some embodiments the electrode assembly is formed by
solid-state plates, wherein the positive and the negative portion
of the plates include thin-film active material produced through
solid state deposition processes. Processes suitable to form active
materials include but are not limited to physical vapor deposition,
chemical vapor deposition, spray deposition, dip coating, spin
coating, electroless deposition, electroplating and any combination
of suitable processes to form thin-film coatings. Suitable forms of
the film materials include materials formed in a high vacuum
process, under an inert gas environment and in room atmosphere and
pressures.
[0123] In some embodiments, the separator material is a thin film
membrane that allows for ionic diffusion and transfer of hydrogen,
oxygen and sulfate ions, e.g. H+, OH--, SO4-- at rates that are
comparable to liquid electrolyte diffusion. In some embodiments,
the separator membrane is a polymeric membrane e.g. Nafion
material.
[0124] In some embodiments the substrate material of the plates is
a suitable thin film electrically conductive medium in a form of a
foil or a solid film, In some embodiments, the thin film is a woven
material selected from the group including metals, e.g. lead,
conductive polymers, e.g. aniline based polymer, conductive
ceramics, e.g. ebonex or conductive tin or titanium oxides. In
various embodiments, the substrate material has a polished surface
with a suitable attachment layer or a patterned surface to promote
adhesion of the active material including holes, ridges, dimples
interlocking features and stress mitigating features.
[0125] In various embodiments, the suitable electrolyte is fully
solid or in the form of a gel or a liquid and dispersed with the
positive and active materials in stoichiometric quantities or
impregnated in the separator membrane or other parts of the
electrode assembly acting as electrolyte reservoirs;
[0126] Alternatively, in some embodiments, the positive and
negative electrode assembly constitutes a fuel cell relying on
separation principles of a ionically conductive membrane. In some
embodiments, a suitable fuel fluid is a gas, e.g. hydrogen or other
suitable fuel.
[0127] The pseudo bi-polar design of each electrode plate may allow
for the spiral configuration to build voltage in the lead-acid
electrochemical cell to any desired value (e.g., 24V, 36V, 42V, or
48V) at a constant capacity, while maintaining a low weight of the
lead-acid electrochemical cell. The low weight may be due to the
sizes of the components of the electrode assembly, as well as the
material-make up of each electrode plate. In addition, the stacking
of the electrode plates at a ninety degree angle relative to one
another may allow for thinner components. For example, in one
embodiment, the electrode assembly 12 may include a diameter of
about 8 inches and may be about 0.3 inches thick. More
specifically, the positive portion 16 of the electrode may be about
0.082 inches thick; the negative portion 20 of the electrode may be
about 0.06 inches thick; the separators 18 may be about 0.06 inches
thick; and the pasting paper 22 may be about 0.004 inches
thick.
[0128] Persons of ordinary skill in the art will understand that
stacking of the electrode plates may be accomplished in any of a
variety of ways. For example, the plates can be stacked so that the
plates build, one upon the other, in a step-wise manner with each
positive 16 and negative 20 portion and their accompanying
connections 26, lying in the same plane, as shown in FIG. 2.
Alternatively, connectors 26 may be angled so that they are offset
by the thickness of a plate, pasting papers and separator, to
facilitate the rise in the plates as they are stacked. As a further
alternative, the electrode plates can be formed having a helical
geometric shape, to facilitate stacking the plates in a helical
pattern, mitigating step discontinuities and reducing stresses on
the connector 26.
[0129] The lead-acid electrochemical cell may further include means
for mitigating shunt currents due to leakage of electrolyte fluid
from the electrodes and separators onto the electrode connectors,
which may cause the electrodes to self-discharge. In one
embodiment, the electrode connectors 26 and inner portion of a
container proximate the electrode plates may be treated with a
hydrophobic coating, which may prevent excess electrolyte fluid
from wetting the electrodes, or electrode connectors 26, or casing.
In other alternative embodiments, the electrode connectors 26 may
be blocked from leaking electrolyte fluid due to barriers formed on
the edges of the positive and negative portions 16, 20 of each
electrode plate. The barrier may be a coating or other material,
including frame material or even excess active material that may
frame each positive and negative portion and contain the
electrolyte. Alternatively, in a further embodiment, the insulator
may have a diameter that is larger than the diameter of both the
electrode assembly the container in which the spiral configuration
resides, such that the insulator may form a barrier with the
container wall and soak up leaking electrolyte fluid.
[0130] FIG. 6 depicts a lead-acid electrochemical module 60
according to an embodiment. The module 60 may include a top portion
34, a bottom portion 38, and a casing 36. Top and bottom portions
34, 38 may enclose the lead-acid electrochemical cell 10 within the
casing 36. Casing may include an inner opening 40, which may be
substantially the same diameter and height of the lead-acid
electrochemical cell 10, such that the lead-acid electrochemical
cell may be fully disposed within the casing 36 and covered by the
top and bottom portions 34, 38. The module 60 may further include
positive and negative terminals (not shown in FIG. 5) attached to
the lead-acid electrochemical cell, such that the module may be
used to provide energy and power.
[0131] As previously disclosed, the spiral configuration may
connect electrode assemblies 12 in order to build voltage while
maintaining a constant capacity of the lead-acid electrochemical
cell. In a second, alternative embodiment, the electrode assemblies
12 may be stacked such that the voltage of the lead-acid
electrochemical cell remains constant while building capacity.
Accordingly, in this second embodiment, instead of the top plate
24D of one electrode assembly 12 being connected to the bottom
plate 24a of another electrode assembly 12, the top and bottom
plates of a single electrode assembly may be connected to complete
the circuit. Each electrode assembly 12 may be connected to a tab
50, which may further be connected to a power bus assembly 500 for
capacity building.
[0132] FIG. 14B illustrates the components of one embodiment of the
power bus assembly 500. Power bus assembly 500 may include a power
bus 502, a terminal 506, a connector piece 504, and a nut 508. In
addition, as shown in FIG. 14B, a bolt 510 may be connected to the
connector piece 504, extend through the power bus 502, and attach
to the nut 508. Bolt 510, when connected to the connector portion
502 and nut 508, may complete the connection of the bus system 500,
which may thereby building capacity.
[0133] As shown in FIG. 14B, connector 504 may include a first
through-hole 504a and a second through-hole 504b formed therein.
First through-hole 504a may connect to the bolt 510, and second
through-hole 504b allow top portion of terminal 506a to extend
there through. Terminal 506 may additionally include a bottom
portion 506b, that may sit atop a top surface of the lead-acid
electrochemical cell 1000. Top portion of terminal 506b may be an
elongate member having a cross section that is substantially the
same shape as the second opening 504b. The bottom portion of
terminal may be flat. Alternatively, as shown if FIG. 14A, the
bottom portion of terminal 506b may have a concave inner
surface.
[0134] Power bus 502 may include an elongate member having a length
that is substantially the same as the height of the lead-acid
electrochemical cell. Power bus 502 may further have slits disposed
along its length, the slits being configured to receive connections
from electrode plates, where the connections are solidified by
compressing the power bus 502 in compression. Further, as shown in
FIG. 14B, a top surface of the power bus 502 may be in contact with
a bottom surface of the connector piece 504, such that the
connector piece 504 may carry current from the power bus 502 to the
terminal 506. Consequently, power bus 502 may be made of any
material known to those skilled in the art that allows for the
carrying of current and the building of capacity.
[0135] Some embodiments utilize an ultrasonically welded power bus.
FIGS. 15A-15D show electro-chemical cells 1500 including welded
power buses 1510 according to some embodiments. Cell 1500 further
includes a plurality of cell packs 1522, which terminate in a
plurality of tabs 1524. In some embodiments, electro-chemical cell
1500 is a battery or a battery module.
[0136] In some embodiments, the power busses are welded to the
cell's end tabs. In some embodiments, the welding is an ultrasonic
welding. FIG. 15A is an assembled view of one end of cell 1500
showing one power bus 1510 welded to tabs 1524. FIG. 15B is an
exploded view of one end of cell 1500 showing one power bus 1510
separate from tabs 1524, which are welded together when assembled.
In various embodiments, ultrasonic welding of the power bus to the
tabs, as compared to other types of joining, reduces the creation
of oxidized metals. Reduced oxidation, in turn, reduces
vulnerability of the power bus to corrosion.
[0137] In various embodiments, power bus 1510 includes a folded
sheet of metal. In various embodiments, power bus 1510 is made from
a sheet of lead, or a sheet of copper. In some embodiments, the
power bus transfers current from the end-cell `tabs` to the battery
terminal. In some embodiments, such as the `ribbon` style power bus
the embodiment of FIG. 15A-15D, the power bus is designed to have
low mass, low electrical resistance, and high environmental or
sulfuric acid corrosion resistance.
[0138] FIG. 15C is a side view of cell 1500 during the welding
process by welding tools 1550, according to some embodiments. In
some embodiments, power bus 1510 starts as a flat sheet of metal.
During the welding process, the sheet of metal is folded and welded
to tabs 1524 by ultrasonic welding tools 1550, as shown in FIG.
15C.
[0139] One of the folds, a cross section of which is shown as
corner 1510-f1, forms a top portion 1510-t and separates it from
the rest of the bus. Further, a front face 1510-f of the power bus
is formed when all tabs on the one side are welded to the folded
power metal sheet. Once the formation of front face 1510-f is
compete and it embeds all tabs, the lower tail of the metal sheet
is folded back to form a back face 1510-b of the power bus. The
competed power bus includes, front and back faces 1510-f and
1510-b, and top surface 1510-t. FIG. 15D shows an assembled cell
1500 with two power busses 1510 welded to the tabs on its two
ends.
[0140] In various embodiments, power bus 1510 provides a balanced
path for conducting electrons from each cell to the battery
terminals. As seen in FIGS. 15A, 15B, and 15D, for example, in some
embodiments each top surface 1510-t is connected to a terminal
1512. Front and back surfaces 1510-f and 1510-b provide electron
paths from tabs 1524 to top surface 1501-t and terminal 1512. In
some embodiments, power bus 1510 is designed with a non-uniform
resistivity along its surface, to provide a balanced, or an
approximately equal, total resistance between each tab 1524 and the
corresponding terminal 1512. In some embodiments, the resistivity
of the front or back surfaces are varied as functions of the
distance from the top surface. In some embodiments, for example,
the resistivity of front surface 1510-f decreases for points that
are farther from top surface 1510-t. In some embodiments, the
resistivity of back surface 1510-b, which provides a shorter path
for lower tabs compared to the upper paths, is higher than front
surface 1510-f. In various embodiments, the resistivity of an area
of the power bus is increased by removing some parts of the surface
to create holes or by decreasing the thickness of the foil forming
the bus. In various embodiments, a desired value of a resistivity
as a function of the location on the power bus foil is determined
by modeling various paths of electrons between the tabs and the
terminals.
[0141] In some embodiments, the base and lid of the casing for a
module include inserts that help increase the stiffness of the
upper and lower surfaces of the casing. FIGS. 15E-15H show a module
1550 with such inserts according to some embodiments. In
particular, FIG. 15E shows an assembled view of module 1550 and
FIG. 15F shows an exploded view of module 1550. Further, FIGS. 15G
and 15H respectively show assembling views of a bottom tray 1554
and a lid assembly 1559 of module 1550.
[0142] As seen in FIG. 15F, module 1550 includes an external base
1552, a lower insert 1553, a skirt 1556, an upper insert 1557, and
an external lid 1558. Lower insert 1553 is used as an insert for
base 1552, and upper insert 1557 is used as an inserted for lid
1558. Inserts 1553 and 1557 add stiffness to the base and lid,
respectively. In some embodiments, the inserts increase the
stiffness of the casing with little additional material and weight.
In some embodiments, the added stiffness helps the module resist
against deformation or bulging of the case. In various embodiments,
without the added stiffness, such bulging can occur due to the
normal cycling of the battery and the resulting increase of gas
pressure inside the battery, which can deform the casing and cause
the bulge. The bulging could result in a loss of compression as
well as non-uniform compression of the electrode stacks.
[0143] As seen in FIG. 15G the bottom tray assembly 1554 is formed
by assembling lower insert 1553 in the external base 1552.
Similarly, FIG. 15H shows that lid assembly 1559 is formed by
assembling upper insert 1557 and external lid 1558.
[0144] FIGS. 15G and 15H also show the formation of the inserts and
their positioning with respect to the other parts, according to
some embodiments. In some embodiments, the inserts include
alignment holes formed therein for proper positioning. In some
embodiments, adhesives are applied to the ribs of the base or the
lid to secure the inserts against them. In some embodiments, the
inserts are bonded to the ribbing in the internal surfaces of the
base or the lid, forming a dual skin assembly. This dual-skin
assembly resists bending loads that may be caused by stack
compression and internal gas pressure.
[0145] In some embodiments, inserts 1553 and 1557 are made of the
same material as the casing 1556. Such material permits a high
degree of flexibility in bonding the parts. In some embodiments,
the inserts are made from polypropylene sheet.
[0146] In some embodiments, the inserts are punched, cut, molded,
formed by other suitable forming techniques. Alternatively, in some
embodiments, the inserts are made from high impact polystyrene
(HIPS); acrylonitrile butadiene styrene (ABS); polyvinyl chloride
(PVC), any suitable composite, or other thermoplastic material that
is acid-resistant, high-strength, and easily formed. In various
embodiments, the inserts provide shielding against electrolyte
leakage.
[0147] In various embodiments, the inserts prevent loss of
compression of the electrodes and maintain even levels of
compression across the electrode stacks. Further, the inserts help
prevent shorting by providing gaps between the electrode stacks
that prevent liquid pathways from forming between adjacent
electrode stacks that may otherwise may cause shorting.
[0148] In some embodiments, the inserts include apertures formed
therein. The apertures permit excess liquid electrolyte to drain
from the electrode stacks to the bottom trench formed in the base.
In addition, the apertures provide pathways for the escape of gas
from the electrode stacks. The inserts can also be formed to
establish pads for positioning the electrode stacks within the
battery.
[0149] In a third embodiment of the present disclosure, the
electrode plates may be rectangular in shape. The rectangular
plates may be similar in area to the semi-circular electrode plates
and may used to form similar-sized electrode assemblies and
modules. For example, FIG. 7 shows a lead-acid electrochemical cell
100 according to a third embodiment of the present disclosure. The
embodiment of FIG. 7 depicts stacking of rectangular electrode
plates at a ninety degree angle relative to one another to form
electrode assemblies, and connecting the electrode assemblies in
the spiral configuration. As shown in FIG. 7, rectangular electrode
plates may be connected to form electrode assemblies, and thereby a
spiral configuration having a square cross-sectional shape.
[0150] Similar to the electrode assembly 12 of FIG. 1, the
electrode assembly 112 of FIG. 8 may include four rectangular
electrode plates 124A-D. Each electrode plate 124A-D may include
positive and negative portions connected by electrode connectors
126. In addition, each electrode plate may include pasting paper
and separators 118. Further, as shown in FIG. 8, each electrode
assembly 112 may be separated by an insulator 114, which may
include the same cross-sectional shape as that of the electrode
assembly 112, and while further may include a radial slit (not
shown).
[0151] FIG. 9 depicts a lead-acid electrochemical cell module 200
according to a third embodiment of the present disclosure. Module
200 may include a casing 140, a slotted tray 142, and a drip tray
146. Slotted tray 142 may include a plurality of slots 144, which
may allow excess electrolyte fluid to flow through the slotted tray
142 and into a collection portion on the drip tray 144. The drip
tray 146 may include outer edges 145, which may be secured to inner
edges of casing 140, such that casing 140 and drip tray 146 may
enclose the lead-acid electrochemical cell 100 sitting atop slotted
tray 142. Casing 140 and drip tray 146 may be secured via any means
known to those skilled in the art. For example, in one embodiment,
casing 140 and drip tray 146 may be held together via plastic
ultrasonic welding.
[0152] The lead-acid electrochemical cell 100 may further include a
tab 50 connected to a positive end and a tab 50 connected to a
negative end of the spiral configuration. Tabs 50 may be securely
connected to the positive and negative ends via any means known to
those skilled in the art. For example, tabs 50 may be connected via
soldering or ultrasonic welding. Tabs 50 may each contain a
through-hole 52, which may allow for passage of posts 148. In
addition, openings 141, 143, 147 in each of the casing 140, slotted
tray 142, and drip tray 146, respectively, may also allow for posts
148 to pass there through.
[0153] As shown in FIG. 10, posts 148 may extend out from
respective openings 141 in the casing 140 so that they may act as
positive and negative terminals for the lead-acid electrochemical
cell module. Posts 148 may further include an end portion 150 with
an opening therein. The opening in the end portion 150 may allow
for individual lead-acid electrochemical cell modules 200 to be
stacked upon one another (FIG. 10).
[0154] A fourth embodiment may employ the square electrode assembly
112 geometry of the third embodiment to build capacity at a
constant voltage, rather than building voltage as in the third
embodiment. Similar to that disclosed in relation to the second
embodiment, this fourth embodiment may include connecting the free
portion of the top plate 124D with the free portion of the first
plate 124A in order to complete the circuit and therefore form a
12V electrode assembly 112. The electrode assemblies may 112 then
be stacked and connected to the power bus assembly 500 in order to
build capacity while maintaining a constant 12V of the lead-acid
electrochemical cell. The fourth embodiment of the lead-acid
electrochemical cell may further include a module that may be
similar to that of the third embodiment.
[0155] The electrode plates may further be used form electrode
assemblies, and thereby lead-acid electrochemical cell
configurations, having a variety of cross-sectional shapes, in
addition to circular and square. This variety of cross-sectional
shapes may allow for stacked or spiral configurations of the
lead-acid electrochemical cell to be placed in a variety of
locations (e.g., in a vehicle) with little or no modification of
the design of the location (e.g., vehicle frame) to accommodate the
lead-acid electrochemical cell system. In these further
embodiments, for example, each electrode assembly may include more
than four plates. In addition, formation of these electrode
assemblies may include stacking of the electrode plates linearly
relative to one another, as well as at a ninety degree angle
relative to one another. For example, in one embodiment,
rectangular plates may be used to form a spiral configuration with
a rectangular cross-section. Accordingly, there may be more
electrode plates along the length of each electrode assembly than
along the width.
[0156] In one embodiment, electrode plates may be oriented such
that resulting electrochemical cells may provide volumetric
efficiency in three orthogonal directions. For instance, the
orientation of the electrochemical cells may provide improved
dimensions in an x-direction, a y-direction, and/or a z-direction,
where the xyz axes are not oriented in any particular way relative
to an electrochemical cell casing. Alternatively, the orientation
of the electrochemical cells may provide improved dimensions in an
x-direction, a y-direction, and/or a z-direction, where the xyz
axes are oriented relative to an electrochemical cell casing. As
described above and below, the electrochemical cells may be united
through ionic connections and a common current collector in such as
way as to build voltage or capacity in the direction of one of the
orthogonal directions x, y, z.
[0157] A fifth embodiment of the present disclosure may include
formation of electrode plates into an electrode assembly, where the
electrode assembly may include an L-shaped cross-section. Each
electrode assembly may include electrode plates with positive and
negative portions connected by electrode connectors. In addition,
each electrode plate may include pasting paper and separators.
Further, each electrode assembly may be separated by an L-shaped
insulator having at least one slit to enable spiral connection of
the L-shaped electrode assemblies. In addition, each electrode
plate may further include means for mitigating shunt currents
(e.g., hydrophobic coating on electrode connectors, hydrophobic
framing of the plates, or an oversized insulator for soaking up
electrolyte fluid).
[0158] The L-shaped lead-acid electrochemical cell may further
include an L-shaped module. Similar to the circular and square
modules, the L-shaped module may include a casing, slotted tray,
and drip tray for collecting leaking electrolyte fluid. There may
further be a tab connected to positive and negative ends of the
L-shaped spiral configuration, such that the tabs may be connected
to shafts that form terminals of the L-shaped lead-acid
electrochemical cell.
[0159] An alternative, sixth embodiment of the L-shaped electrode
assemblies may further include a capacity building geometry,
similar to the other capacity-building embodiments disclosed
herein. The L-shaped electrode assemblies in the sixth embodiment
may each be connected in parallel, with each assembly terminating
in a tab, with each of the respective tabs connected to the power
bus assembly 500. The capacity-building L-shaped electrochemical
cell may be housed within a module that is similar to the L-shaped
module for the spiral configuration.
[0160] A seventh embodiment of the present disclosure may an
electrode assembly having a U-shaped cross-sectional shape. The
seventh embodiment may build voltage at a constant capacity, as
disclosed herein. Alternatively, an eighth embodiment may include a
U-shaped electrode assembly disposed to build capacity. FIG. 17
illustrates a lead-acid electrochemical cell 2000 according to an
eighth embodiment of the present disclosure. The lead-acid
electrochemical cell 2000 may include a plurality of electrode
assemblies 2012 stacked, such that voltage may remain constant
while capacity may be built. Each electrode assembly 2012 includes
the U-shaped configuration, such that the lead-acid electrochemical
cell 2000 may fit within a module that may include an intermediate
separator 2104. The lead-acid electrochemical cell 2000 may further
include a power bus 500 on each end to build capacity.
[0161] As a further alternative, the electrochemical cell may be
configured in an elongated rectangular shape. FIG. 11 illustrates
an electrode plate 1024 of a lead-acid electrochemical cell
according to a ninth embodiment of the present disclosure. Similar
to the electrode plates 24, 124 in FIG. 4A and FIG. 8, the
electrode plate 1024 may include a first, positive portion 1028 and
a second, negative portion 1030, with electrode connectors 1026
there between. In various embodiments, each electrode plate portion
1028 or 1030 has a width 1028-W in the direction of electron flow
and a length 1028-L perpendicular to that direction. In various
embodiments, each electrode plate has an aspect ratio, that is, a
ratio of its length to its width (the length of 1028-L over the
length of 1029-W) that is larger than one. In some embodiment, the
ratio of length to width is about 1.5. In some other embodiments
this ratio is about 2.0. Such aspect ratios increase the efficiency
of the batter cells as, for the same total surface of the electrode
pates, the electron requires to travel a shorter path.
[0162] In the ninth embodiment, as shown in FIG. 12, the electrode
assembly may be disposed in parallel in a capacity-building
configuration. As shown in FIG. 12, electrode assemblies may be
formed by aligning a desired number of electrode plates 1024, which
may form the bottom portion of the electrode assembly. The top
portion of the electrode assembly may be formed by aligning a
positive portion 1028 of a top plate with a negative portion 1030
of a bottom plate, and so on. Separators may be located between
each of the stacked positive and negative portions. In addition,
formation of the electrode assembly may result in a free positive
portion 1028 of a bottom electrode plate 1024 at one end, and a
free negative portion 1030 of a bottom electrode plate 1024 at the
opposite end. Individual negative and positive portions,
respectively may be placed on these free ends in order to complete
the circuit. Electrode assemblies may be formed of any desired
voltage. For example, the electrode assembly 1010 of FIG. 12 may be
12 volt assembly.
[0163] FIG. 13 illustrates a lead-acid electrochemical cell 1000,
which may include the stacked electrode assemblies 1024 of FIG. 12.
The lead-acid electrochemical cell 1000 may include tabs 50.
Similar to the tabs 50 in the lead-acid electrochemical cell 100 of
FIG. 7, each tab may include a through-hole 52 and may be connected
via soldering or ultrasonic welding to a positive end and a
negative end of each electrode assembly. FIG. 13, however,
illustrates that tab 50 may be connected to two electrode
assemblies, as opposed to only one.
[0164] FIG. 14A further illustrates that each end of the lead-acid
electrochemical cell 1000 may be connected to a power bus assembly
500, which may allow for the individual electrode assemblies 1024
to be connected in parallel in order to build capacity of the
lead-acid electrochemical cell 1000.
[0165] FIG. 16 illustrates a lead-acid electrochemical cell module
1200 including the lead-acid electrochemical cell 1000 of FIG. 14A.
Similar to the lead-acid electrochemical cell module 200 of FIG. 9,
the lead-acid electrochemical cell module 1200 may include a casing
1202, a slotted tray 1204 with a plurality of slots 1205, and a
drip tray 1206 for collecting electrolyte fluid that seeps through
the slots 1205 of the slotted tray. The casing 1202, slotted tray
1204, and drip tray 1206 may include a length, width, and height
that are slightly larger than the dimensions of the lead-acid
electrochemical cell 1000, such that the casing 1202 and drip tray
1206 may completely enclose the lead-acid electrochemical cell
1000. Further, similar to the module 200 of FIG. 10, the casing
1202 and the drip tray 1206 may be held together via any process
known to those skilled in the art, including, but not limited to
plastic ultrasonic welding.
[0166] Various embodiments use novel shapes for the electrode
plates and accordingly increase the charge capacity or efficiency
of the battery. FIG. 19A shows a circular plate module 1900 in
accordance with some embodiments of the present disclosure.
Circular plate module 1900 includes two caps 1910 at the top and
bottom; a plurality of circular plates 1920 between the two caps;
and a plurality of nuts and bolts assemblies 1930 (labeled as two
end-nuts-and-bolts assemblies 1930a and four side-nuts-and-bolts
assemblies 1930b). Top and bottom caps 1910 are tightened by the
plurality of nuts and bolts assemblies 1930 on the two sides of the
plurality of circular plates 1920, and hold those plates together.
Moreover, top and bottom caps 1910 each includes a terminal 1912
(visible in FIG. 19A for top cap only) through which the module
connects to a terminal of the battery or another module.
[0167] FIG. 19B shows a disassembled view of circular plate module
1900 and its various parts in accordance with some embodiments. In
particular, in FIG. 19B, module 1900 includes one layer positive
terminal 1920P, one layer negative terminal 1920N, five layer
electrodes 1920E, six bolts 1930B, six nuts 1930N (of which four
are visible), and four bushings 1932 (of which three are
visible).
[0168] In the embodiments of FIGS. 19A and 19B, the disassembled
parts shown in FIG. 19B combine into assembled module 1900 of FIG.
19A. In particular, when assembling the parts shown in FIG. 19B
into assembled module 1900 of FIG. 19A, the bolts 1930B pass
through designated holes in layer positive terminal 1920P, either
designated holes in layer electrodes 1920E or bushings 1932, and
designated holes in layer negative terminal 1920N, and then engage
nuts 1930N. More specifically, two of the bolts, marked by arrows,
correspond to end-nuts-and-bolts assemblies 1930a in FIG. 19A, and
pass through the holes in layer electrodes 1920E. The other four
bolts correspond to side-nuts-and-bolts assemblies 1930b in FIG.
19A and pass through bushings 1932.
[0169] When assembling the module shown in FIG. 19B, layer
electrodes 1920E and layer negative or positive terminals are
positioned on top of each other with a half turn for each layer
compared to the previous, such that the positive half layers of one
plate is positioned right below the negative half layer of the next
plate, or vice versa.
[0170] Various embodiments use different combinations of layer
electrodes and layer negative or positive terminals to result in
various battery powers for the module. For example, in some
embodiments such as the one shown in FIG. 19B, module 1900 includes
five layer electrodes 1920E placed between one layer positive
terminal 1920P and one layer negative terminal 1920N. In some
embodiments, such a combination of electrodes provides a twelve
volt battery module.
[0171] FIG. 19C shows a detailed structure of layer electrode 1920E
according to some embodiments. In FIG. 19C, layer electrode 1920E
includes negative half layer 1924, positive half layer 1926, wire
substrate 1920W, two thin separator half layers 1927t-1 and
1927t-2, thick separator half layer 1927T, circular frame 1920F,
frame o-ring 1921, and insulator half layer 1925.
[0172] These parts are assembled in the order and orientations
shown in FIG. 19C to generate one layer electrode 1920E shown in
FIG. 19B, in accordance to some embodiments. In particular wire
substrate 1920W is strung over circular frame 1920F to create a
wire mesh. This mesh is then embedded in the active materials
included in negative and positive half layers 1924 and 1926 to form
an active material layer. An o-ring 1921 is included for sealing
the gap between two subsequent electrode layers. Negative half
layer 1924 is then covered underneath by, in order, thin separator
half layer 1927t-1, insulator half layer 1925, and thin separator
half layer 1927t-2. Positive half layer 1926, on the other hand, is
covered underneath with a thick separator half layer 1927T.
[0173] In various embodiments, layer electrodes 1920E are assembled
such that negative and positive half layers of abutting layer
electrodes come in contact. In particular, when a second layer
electrode 1920E is positioned over a first layer electrode to form
a module 1900, such as that seen in FIG. 19B, the second one is
rotated with respect to the first one by 180 degrees around its
central axis. In this manner, the negative half layer of the second
layer electrode is positioned on top of the positive half layer of
the first layer electrode and the positive half layer of the second
layer electrode is positioned on top of the negative half layer of
the first layer electrode, in each case with some separators or
insulators coming between them. For example, in one set-up, the
exploded view shown FIG. 19C represents the first layer electrode
sandwiched between a second layer electrode on top and a third
layer electrode at the bottom. The second and third layer
electrodes, not shown, will be oriented similar to each other, but
rotated by 180 degrees with respect to the first layer electrode.
In this exemplary set-up, negative half layer 1924 of the first
layer is sandwiched between the positive half layers of the second
and third layer electrodes, with a thick separator half layer
coming before the positive half layer above it, and thin separator
1927t-1, insulator 1925, and thin separator 1927t-2 respectively
coming before the positive half layer below it. In a similar
manner, positive half layer 1926 of the first layer electrode is
sandwiched between negative half layers of the second and third
layer electrodes, with a thin separator half layer, an insulator
half layer, and another thin separator half layer coming before the
negative half layer above it, and the thick separator 1927T coming
before the negative half layer below it.
[0174] In various embodiments, the insulator half layer is an
insulating layer that prevents the active half layers on its two
sides from exchanging charges. In the above described exemplary
set-up, for instance, the insulator half layer of the second layer
electrode prevents positive half layer 1926 of the first layer
electrode from exchanging charges with the negative half layer of
the second layer electrode located above it. Similarly, insulator
half layer 1925 prevents negative half layer 1924 from exchanging
charges with the positive half layer of the third layer electrode
located below it.
[0175] In various embodiments, the separator half layer is an
ionically conductive layer that is in contact with one or two
active half layers. In some embodiments, the separator half layer
preserves some of the electrolyte in the active half layer to which
it contacts. Further, in various embodiments, the separator half
layer is in contact with two active half layers on its two sides,
enables ionic charge exchanges between those half layers, thus
forming a unit cell. In the above described exemplary set-up, for
instance, thin separator half layer 1927t-1 is in contact with
negative active material 1924 above it and preserves and exchanges
ions with that negative half layer. Similarly, thin separator half
layer 1927t-2 is in contact with a positive active material located
below it. Thick separator half layer 1927T, on the other hand,
enables ionic charge exchanges between positive half layer 1926 of
the first layer electrode and the negative half layer of the third
layer electrode below. Similarly, the thick separator half layer of
the second layer electrode enables ionic charge exchanges between
negative half layer 1924 and the positive half layer electrode of
the second layer electrode. This combination of positive half
layer, separator half layer, and negative half layer creates a unit
cell inside module 1900. Thus in FIG. 19C, for example, negative
half layer 1924 forms a unit cell with the positive half layer
above it, while being insulated from the positive half layer below
it. Similarly, positive half layer 1926 forms a second unit cell
with the negative half layer below it, while being insulated from
the negative half layer above it. These unit cells of the module
are connected to each other in series via wire substrate 1920W.
[0176] In various embodiments, the wire substrate is a mesh created
by a single-direction conductive wire, which enables conductive
electron exchanges between the two active half layers that it
connects. The wire substrate thus connects within the same layer
electrode the positive half layer of one unit cell to the negative
half layer of another unit cell. In various embodiments, the wire
substrate has a composition and a design that increases the
efficiency of the battery. In some embodiments, such as that shown
in FIG. 19C, the wiring is a mesh of directional wires that extend
from one electrode to the other electrode. Further, in various
embodiments, the wire substrate is made of a non-crystalline
amorphous material that does not have a long range order. Such
materials provide a better resistance against corrosion and thus
are more suitable to be used in contact with the electrolytes.
[0177] In the above-described exemplary set-up, for instance, in
the first layer electrode shown in FIG. 19C, wire substrate 1920W
connects negative half layer 1024, belonging to the first unit
cell, to positive half layer 1926, belonging to the second unit
cell.
[0178] In various embodiments, circular plate module 1900 includes
a set of unit cells connected in series. In some embodiments, each
unit cell the middle is formed between two abutting layer
electrodes, in the manner detailed above. Further, two end unit
cells are formed between a layer electrode and an abutting layer
positive terminal or layer negative terminal. For example, in the
embodiment shown in FIG. 19B, the first layer electrode terminal
1920E-1 includes a negative half layer 1924-1, which forms a unit
cell with positive half layer 1926-P in layer positive terminal
1920P. The fifth layer electrode 1920E-5, on the other hand,
includes a positive half layer 1926-5, which forms a unit cell with
negative half layer 1924-N in layer negative terminal 1920N.
[0179] FIGS. 19D and 19E show the structure of the layer positive
terminal and the layer negative terminal in more detail and in
accordance with some embodiments. FIG. 19D shows that layer
positive terminal 1920P includes, in consecutive layers starting
from top, cap 1910; thin separator half layer 1027t-1 along with a
lead sheet half layer 1954; positive half layer 1926; wire
substrate 1920W; thick separator half layer 1927T along with a
gasket half layer 1952; and insulator 1925 and thin separator half
layer 1027t-2. Layer positive terminal 1920P also includes circular
frame 1920F, frame o-ring 1921, a terminal 1956 and a terminal
o-ring 1957.
[0180] FIG. 19E shows that layer negative terminal 1920N includes,
in various layers starting from bottom, cap 1910; PVC half layer
1958 along with holed gasket half layer 1952h; another PVC half
layer 1958 along with holed PVC half layer 1958h; insulator 1925
along with another holed PVC half layer 1958h; thin separator half
layer 1927t along with lead sheet half layer 1954; wire substrate
1920W; and negative half layer 1924 along with gasket half layer
1952. Layer negative terminal 1920N also includes circular frame
1920F, frame o-ring 1921, a long terminal 1956L and terminal o-ring
1957.
[0181] In some embodiments PVC is used to manufacture circular
frame 1920F, insulator half layer 1925, cap 1910, and PVC half
layers 1958 and 1958h. Moreover, lead is used to manufacture wire
substrate 1020W, terminals 1956 and 1956L. Further, EPDM rubber of
70 A durometer is used in manufacturing o-rings 1921 and 1957, and
gasket half layers 1952 and 1952h.
[0182] Parts 1924 and 1926 are respectively the negative and
positive active materials. Thin and thick separators 1927t and
1927T are made of fiberglass mats of different thicknesses. In
particular, in the embodiment shown in FIGS. 19C-19E, thick
separator half layer 1927T is thicker than thin separator half
layer 1927t. Moreover, positive active material 1926 is thicker
than negative active material 1924. In these embodiments, thin
separator half layer 1927t is included on the side that also
includes negative half layer 1924 to compensate for the smaller
thickness of negative half layer 1924 compared to positive half
layer 1926. Moreover, as explained, separator half layers 1927
preserve the electrolyte of the active layer with which they
contact.
[0183] In various embodiments, the layer electrodes are assembled
into a circular plate module in a manner that provide a continuous
charge path among the plates. FIG. 19F shows the charge path of an
assembly of layer electrodes, including layer electrodes 1920E-1 to
1920E-4, in a circular module 1900 in accordance with some
embodiments. In FIG. 19F, vertical and horizontal arrows indicate
direction of charge transfer. Specifically, horizontal arrows 1942
indicate a conductive electron transfer from one unit cell to the
next unit cell in the assembly, through a wire substrate. Vertical
arrows 1944, on the other hand, indicate ionic charge transfer
within a unit cell. an ionic charge transfer through a separator
from the left hand side (positive) half layer of layer electrode
1920E-2 to the left hand side (negative) half layer of layer
electrode 1920E-3. In some embodiments, the voltage produced by a
unit cell is around two volts. In the embodiment shown in FIG. 19B,
for example, module 1900 assembles six unit cells and the total
voltage generated by module 1900 is around twelve volts.
[0184] In various embodiments, layer electrodes 1920E or layers for
positive and negative terminals are manufactured by assembling its
various parts in some specific order. In the embodiment shown in
FIG. 19C, for example, when manufacturing layer electrode 1920E,
wire substrate 1920W can be strung into the grooves etched on the
upper face of circular frame 1920F to create a wired-frame
assembly. This wired-frame assembly can then be covered on the one
side with negative active material to form negative half layer 1924
and on the other side with positive active material to form
positive half layer 1926. Insulator and separator half layers 1925
and 1927 can then be attached on the appropriate faces of the
negative and positive half layers
[0185] Different embodiments use different structures for the
wired-frame assembly or for combining the wired-frame assembly with
the remaining parts of a an layer electrode. FIG. 21 shows two
circular frames 2120E-1 and 2120E-2 in accordance with two
different embodiments. Circular frame 2120E-1 has wire grooves 2152
etched on a section of its perimeter in a manner that a wire
substrate strung into the grooves does not leave the perimeter of
the frame and does not touch the perimeter of the wired-frame
assembly. Circular frame 2120E-2, on the other hand, has wire
grooves 2154 etched along the length of its perimeter in a manner
that a wire substrate strung into the grooves forms part of the
perimeter of the wired-frame assembly. In some embodiments using
circular frame 2120E-2, frame o-ring 1921 is used to seal the
perimeter of the wired-frame assembly and prevent electrolyte from
leaking out.
[0186] FIG. 22 shows the structure of a circular frame 2220F in
accordance with some other embodiments. Circular frame 2220F
includes a perimeter section 2220Fp, a central diameter section
2220Fd, and an O-ring sealing 2258. Perimeter section 2220Fp has
grooves formed on it for the wire substrate in the form of vertical
channels 2254. Diameter section 2220Fd, on the other hand, has
grooves formed on it for the wire substrate in the form of
horizontal channels 2256.
[0187] O-ring sealing 2258 provides a sealing mechanism to prevent
leakage of the byproducts, such as acids, or gases generated by the
battery. Moreover, in some embodiments, such leakage is also
prevented in the center by cutting out along diameter section
2220Fd, a channel such as potting compound area 2257. After
lead-wire substrate is strung on circular frame 2220F, an epoxy is
poured into area 2257 to seal in the wire. In some embodiments, the
epoxy can be wax or other suitable hydrophobic materials. The epoxy
is used to prevent or reduce the leakage of the battery between
half layers.
[0188] Various embodiments change the shape or geometry of the
module covers to improve the characteristics of the battery. FIG.
23 shows a circular module cap 2300 in accordance with one
embodiment. Module cap 2300 includes six sectors 2302 and a
terminal location 2304. Each of sectors 2302 includes a middle
section, which has a reduced thickness and is a surrounded by a
thicker rim. Because of the reduced thickness in the middle of
sectors 2302, module cap 2300 is lighter than a cap that has a
uniform thickness and is otherwise similar to module cap 2300. For
example, in some embodiments each circular module cap 2300 for the
top or bottom covers measures eight inches in the outside diameter,
seven inches in the inside diameter, and 1/4 inches in thickness.
In various embodiments, top and bottom covers are injection molded
using PVC. In these embodiments, module cap 2300 weighs around 140
grams, while a similarly dimensioned cap with a uniform thickness
weights around 270 grams. Lighter covers reduces the weight of the
battery, and thus increases its specific energy or specific
power.
[0189] FIG. 20 shows an electrode assembly 400 of a battery module
according to some embodiments. Assembly 400 includes semi-circular
shaped full electrode plates 402, quarter-circular shaped positive
and negative end plates 404 and 406, isolator layer 408, separator
plates 410, positive terminal 412 and negative terminal 414. Each
full electrode plate 402 includes a positive half plate 402P and a
negative half plate 402N. Full electrode plates 402 are assembled
in a manner that when a full plate is positioned above another full
plate, it is rotated by 90 degrees about the axis of electrode
assembly 400, such that positive half plate 402P of one plate is
positioned against negative half plate 402N of the other plate.
Moreover, a separator 410 is inserted between these two oppositely
charge half plates to provide ionic connection between them. This
combination of negative half plate of one plate ionically connected
to a positive half plate of another plate located over or under the
first plate creates a unit cell. Moreover, the wire connection
between the positive half plate 402P and negative half plate 402N
in the same full plate 402 provides a series connects between two
consecutive unit cells. Positive end plate 404 forms a unit cell
with the negative half plate 402N positioned against it (under it
in FIG. 20). Similarly, negative end plate 406 forms another unit
cell with the positive half plate 402P positioned against it (above
it in FIG. 20).
[0190] FIG. 24 shows the behavior of calculated capacity of
circular plate modules as a function of the diameter of the
circular plates, in accordance with some embodiments. FIG. 24
depicts graph 2400 in which abscissa 2410 lists the electrode
diameter in inches and ordinate 2420 lists the corresponding
calculated capacity in Ampere Hours (ah). The curve 2430 shows the
calculated values for the capacity as a function of the diameter.
In particular, curve 2430 shows that increasing the diameter of the
plates causes the calculated capacity to increase in a non-linear
manner. Moreover, curve 2430 shows that, in one embodiment, the
electrode diameter is set to seven inches and the capacity of the
module is around 6.5 ah.
[0191] In some embodiments, a battery module is made of plates that
have non-circular shapes. FIG. 25 shows a battery 2500 shaped as a
rectangular box (rectangular prism) in accordance with some
embodiments. Battery 2500 includes one or more rectangular plates
2510. In some embodiments, rectangular plate 2510 includes a
rectangular active module 2520 and a rectangular nest module
2530.
[0192] Rectangular active module 2520 fits inside rectangular nest
module 2530. Rectangular active module 2520 includes a rectangular
frame 2520F that houses a rectangular negative half layer 2524 and
a rectangular positive half layer 2526. Rectangular nest module
2530, on the other hand, contains a rectangular isolator 2525 and a
rectangular separator 2527.
[0193] In various embodiments, two different frames thus comprise
one layer of the battery module, in a manner similar to that shown
in FIG. 25. A first frame contains two active half layers including
two different types of active materials. The second frame has the
same shape as the first frame and includes a separator or an
isolator, or both. In various embodiments, these two types of
frames are manufactured separately and are then put together to
create one layer of a battery module. Multiple layers are then
assembled to create the battery module. In some embodiments, when
assembling the layers, each layer is rotated with respect to the
layer below or above it, such that the negative and positive half
layers of neighboring layers face each other.
[0194] In some embodiments, a number of rectangular layers are
assembled to form a rectangular module with a desired output
voltage. FIGS. 26A and 26B show a 12 volt rectangular module 2600
in assembled and disassembled forms according to some embodiments.
As shown in FIG. 26B, rectangular module 2600 includes a top layer
2610, five current repeating frames 2630, and a bottom layer 2650.
Top layer 2610 includes a top cover 2610C and an upper
half-electrode frame 2620. Bottom layer 2650 includes a bottom
cover 2650C and a lower half-electrode frame 2640. In the
embodiment shown in FIGS. 26A and 26B, upper half electrode frame
2620 includes a negative half layer and lower half electrode frame
2640 includes a positive half layer, similar to positive and
negative half layers discussed above. In various embodiments,
module 2600 can be oriented and used differently such that, for
example, the negative and positive half layers are respectively
positioned at the bottom and at the top, or in any other
orientation.
[0195] FIGS. 26C and 26D respectively show assembled and
disassembled views of center repeating frame 2630 of module 2600
according to some embodiments. As shown in FIGS. 26C and 26D,
current repeating frame 2630 includes a gasket, a negative acid
reservoir half rectangle, positive and negative active material
half rectangles, a wire substrate, a potting compound, an inner
frame, a separator half rectangle, a positive acid reservoir half
rectangle, and an outer frame that includes an isolator half
rectangle. These parts generally function in a manner similar to
the parts of layer electrodes discussed above. In particular, in
some embodiments, negative and positive acid reservoir half
rectangles are made of thin separator material. In the embodiment
shown in FIG. 26D, negative and positive acid reservoirs
respectively cover negative and positive active material half
rectangles from above or below, and each function as a reservoir of
acid for the corresponding active material half rectangle. In some
embodiments the gasket is made of EPDM rubber, other embodiments
include Viton or similar elastomers, and acts as a washer between a
center repeating frame and the one above it. The inner frame is
made of a suitable acid resistant plastic and functions as a
general frame for the active material, the wire substrate, the acid
reservoirs, and other parts. The potting compound is a curable
epoxy compound and functions as a barrier for acid migration
between positive and negative active material
[0196] FIGS. 26E and 26F respectively show assembled and
disassembled views of top layer 2610 of module 2600 according to
some embodiments. Top layer 2610 includes top cover 2610C and upper
half-electrode frame 2620. FIG. 26F also shows, in accordance with
some embodiments, different parts of upper half-electrode frame
2620 which include a gasket, a negative terminal, a current
collector, a negative acid reservoir half rectangle, a potting
compound, a wire substrate, an active material half rectangle that
is negative, a separator half rectangle, a spacer half rectangle,
and an outer frame that includes a separator half rectangle. The
current collector is made of a lead metal sheet and collects
current from the active material and delivers it to the negative
terminal. The spacer half rectangle is made of EPDM rubber or
similar acid resistant elastomer and compensates for thickness
difference between the substrate and isolator components.
[0197] FIGS. 26G and 26H respectively show assembled and
disassembled views of bottom layer 2650 of module 2600 according to
some embodiments. Bottom layer 2650 includes bottom cover 2650C and
lower half-electrode frame 2640. FIG. 26H also shows, in accordance
with some embodiments, different parts of lower half-electrode
frame 2640 which include a gasket, an active material half
rectangle that is positive, a spacer, a wire substrate, a potting
compound, an inner frame, an acid reservoir for positive plate, an
outer frame that includes an isolator half rectangle, a current
collector, a positive terminal, and a second gasket.
[0198] Various embodiments combine a larger number of rectangular
frames to create rectangular modules with a larger output. FIGS.
27A and 27B show a 192 volt rectangular module 2700 according to
one embodiment. Rectangular module 2700 includes a lid 2710,
positive bus 2722 and negative bus 2724, two electrode stacks 2730,
center bus 2740, and case 2750. In this embodiment the center bus
connects the lower terminal of stacks 2730 together in a series
electrical connection.
[0199] Some embodiments use a spiral configuration of unit cells.
In some embodiments, the spiral configuration provides a
multi-helix current path through the electrode stack. FIGS. 28A-D
show a circular spiral module 2800 according to some embodiments.
Circular spiral module 2800 includes a plurality of partial modules
2810 assembled in a spiraling manner, as described below in more
detail.
[0200] FIGS. 28B and 28C show details of partial module 2810
according to some embodiments. Partial module 2810 is shaped as a
sector of a circle. In the embodiment shown in FIGS. 28A-D, partial
module 2810 is shaped as a 60 degree angle sector including two 30
degree half sectors with positive and negative active
materials.
[0201] FIGS. 28B and 28C show various parts of partial module 2810.
Partial module 2810 includes frame 2812, positive and negative
active material half sectors 2814 and 2815, wire substrate 2816,
isolator half sector 2817, and separator half sector 2818. The
negative and positive active materials, the isolator, and the
separator function in a manner similar to that explained above in
circular plate module 1900 or other similar modules.
[0202] FIGS. 28A and 28D show the stacking of multiple partial
modules 2810 to form circular spiral module 2800, according to some
embodiments. In particular, as shown in FIG. 28D, circular spiral
module 2800 includes five partial modules 2810-1 to 2810-5. The
partial modules are stacked in a spiral manner so that the negative
half sector of a partial module is located underneath and connected
ionically to the positive half sector of the partial module above
it. For example, the negative half sector of partial module 2810-1
is located underneath and connected ionically via a separator to
the positive half sector of partial module 2810-2. Similarly, the
negative half sector of partial module 2810-2 is located underneath
and connected ionically via a separator to the positive half sector
of partial module 2810-3, and so on.
[0203] In this manner, a set of partial modules 2810 form a group
of unit cells connected in series. In particular, each unit cell
includes the negative half sector of partial module 2810-i, the
positive half sector of the partial module 2810-i+1 located above
the negative half sector, and the separator between these two half
sectors. Each unit cell, thus formed, is connected in series with
the cells before or after it by the trans-electrode substrates
2816. For example, one unit cell forms between the negative half
sector of partial module 2810-1 and the positive half sector of
partial module 2810-2 located above it. This unit cell is connected
serially to the unit cell before and after it respectively by the
trans-electrode substrate 2816 in partial modules 2810-1 and
2810-2.
[0204] In FIG. 28D, the arrows show the direction of the electrons
transferred inside and among these serially connected unit cells.
In particular, each horizontal arrow shows the conductive transfer
of charge from one unit cell to the next one, that is, from the
positive half sector of each partial module 2810-i to the negative
half sector of the same partial module through the trans-electrode
substrate of that partial module. Each vertical arrow, on the other
hand, shows the ionic transfer of current within each unit cell,
that is, from the negative half sector of a partial module 2810-i
to the positive half sector of the next partial module 2810-i+1
positioned above the negative half sector through the separator
inserted between them. Thus, partial modules 2810-1 to 2810-5 form
a serially connected set of four unit cells and two half sectors at
the start and the end. Some embodiments include a gasket which
prevents internal shorting or electrolyte loss. In some embodiments
a gasket prevents electrolyte loss in a manner similar to that
explained above in circular plate module 1900 or other similar
modules. In FIG. 28C, for example, internal shorting is mitigated
by the current isolator 2817.
[0205] In some embodiments an electro-chemical battery module is a
cylindrical spiral wound module. The cylindrical spiral wound
module utilizes an alternative form factor and an alternative
manufacturing method. In some embodiments, the module is built by
winding long strip electrodes of mono- and bipole configurations
around a center mandrel to create cylindrical cells for the module.
Adjacent cells are connected in electrical series to one another
through wire substrates. The cells are housed in a cylindrical,
pressure tight case. Cylindrical spiral wound modules, thus built,
have fewer parts, higher volumetric efficiency, and higher
vibration and pressure resistance compared to their
counterparts,
[0206] FIGS. 29A-29C show spiral wound modules 2900 according to
various embodiments. In particular, FIG. 29A shows an external
view, FIG. 29B shows a view of the internal assembled parts, and
FIG. 29C shows an exploded view of the parts of spiral wound module
2900 according to various embodiments.
[0207] Spiral wound module 2900 includes a module case 2902, a case
vent 2904, a top cover 2906, a positive terminal 2908, a negative
terminal 2910, a positive current collector 2912, a positive
half-electrode substrate termination strip 2914, a cylindrical cell
pack 2916, a negative half-electrode substrate termination strip
2918, a negative current collector 2920, a center mandrel 2922, and
a bottom cover 2924. In the embodiments shown in FIGS. 29A-29C,
cylindrical cell pack 2916 includes six cylindrical cell stacks
2917, connected internally in series via wirings. In some
embodiments, each cell stack 2917 provides a two volt potential
difference, and thus module 2900 is a twelve volt module.
[0208] In various embodiments, positive half-electrode substrate
termination strip 2914 electrically joins positive half-electrode
end wiring in a common bus along outer edges and allows easy
electrical joining of wiring to positive current collector 2912. In
various embodiments, positive current collector 2912 is a circular
metal plate that electrically joins positive half-electrode
termination strip to positive terminal 2908. In some embodiments,
positive current collector 2912 is a low resistance, direct line
path to the positive terminal. In various embodiments, positive
terminal 2908 allows external electrical connection to the
module.
[0209] Similarly, in various embodiments, negative half-electrode
substrate termination strip 2918 electrically joins negative
half-electrode end wiring in a common bus along outer edges and
allows easy electrical joining of wiring to negative current
collector 2920. In various embodiments, negative current collector
2920 is a circular metal plate that electrically joins negative
half-electrode termination strip to negative terminal 2910. In some
embodiments, negative current collector 2920 is a low resistance,
direct line path to the negative terminal. In various embodiments,
negative terminal 2910 allows external electrical connection to the
module.
[0210] FIGS. 29D and 29E depict an intermediate stage of
manufacturing a cylindrical cell pack similar to cylindrical cell
pack 2916 according to some embodiments. FIGS. 29D and 29E each
show two different views of a flat cell pack 2966 while being
rolled into a cylindrical cell pack. Flat cell pack 2966 includes
six flat cell stacks 2970 and a center mandrel 2972. At the stage
shown in FIGS. 29D and 29E, each cell stack 2970 is a flat
elongated strip. In the embodiment shown in FIGS. 29D and 29E, each
cell stack 2970 includes four layers as described in more detail in
relation to FIG. 30A. In particular, each cell stack 2970 includes
alternating layers of electrodes and separators. The ends of those
layers are staggered in FIGS. 29D and 29E for illustration
purposes. Some of neighboring layers of the cell stacks are
connected via wirings, as detailed below.
[0211] FIGS. 29D and 29E depict a starting stage of rolling flat
cell stacks 2970 around center mandrel 2972 to build a cylindrical
cell pack. FIGS. 29D and 29E also show positive and negative half
electrode termination strips 2974 and 2976 in their flat
configuration, and while being rolled around center mandrel 2972.
After the completion the rolling, these strips will take the spiral
shape of parts 2914 and 2918 in FIG. 29C.
[0212] In some embodiments, center mandrel 2972 is a cylindrical
tube, made of a sulfuric acid-resistant plastic. In some
embodiments the material of center mandrel is similar to the
material of the module case. In various embodiments, the electrodes
are wound around the center mandrel. In various embodiments, center
mandrel 2972 thus supports the electrode assembly. FIG. 30A is a 2D
sketch showing full- and half-electrode arrangement on the mandrel
prior to winding.
[0213] FIG. 30A shows a cross section of a spiral wound module upon
performing one roll of winding the cell stacks around the central
mandrel. A sequence of images 3001-3005 are used to show details of
a cell pack 3000 according to some embodiments. In particular, the
full cell image 3005 shows a cross section of cell pack 3000 that
includes layers resulting from winding a flat cell pack such as
cell pack 2966 in FIGS. 29D and 29E around a center mandrel 3020
after one full rolling. After being wound for one roll, cell pack
3000 includes six cell stacks 3010. Each rectangle in FIG. 30A
represents a cross section of a layer of a cell stack, rolled
around center mandrel 3020.
[0214] Image 3001 shows a central mandrel 3020. Image 3002, shows a
layer of separator layer 3030 formed around central mandrel 3020
upon performing one roll of winding the cell stacks around the
central mandrel. Separator layer 3030 includes six separator half
parts 3032. Each separator half part 3032 corresponds to one of the
six cell stacks 3010. In some embodiments, separator layer 3030 is
made of absorbent glass mat (AGM). In various embodiments, the
separator layer holds electrolytes, such as sulfuric acid and
promotes ionic transfer between the positive and negative
electrodes of the cell.
[0215] Image 3003 shows an electrode layer 3040, formed around
separator layer 3030 upon performing one roll of winding the cell
stacks around the central mandrel. Electrode layer 3040 includes
three negative half electrodes 3042 and three positive half
electrodes 3044, laid over the six separator half parts 3032 in
alternating order. In particular (assuming that in stage 3003 of
FIG. 30A the six half electrodes in electrode layer 3040 are
numbered from left to right) first, third, and fifth half
electrodes are positive half electrodes 3044; and second, fourth,
and sixth half electrodes are negative half electrodes 3042.
[0216] The three consecutive neighboring pairs of negative and
positive half electrodes are connected via three wirings. That is,
as shown in image 3003, three pairs respectively consisting of the
first and second half electrodes, the third and fourth half
electrodes, and the fifth and sixth half electrodes are each
connected via a wiring 3046 (of which, in FIG. 30A, all wirings are
shown and only the first wiring has been labeled). Each such
connected pair forms a bipole electrode 3048 (of which, in FIG.
30A, only the first one has been labeled). Electrode layer 3040,
therefore, includes three bipole electrodes 3048.
[0217] Image 3004 shows a second separator layer 3050 that is
formed around electrode layer 3040 upon performing one roll of
winding the cell stacks around the central mandrel. Separator layer
3050 includes six separator half parts 3052. Each separator half
part 3052 corresponds to one of the six cell stacks 3010.
[0218] Image 3005 shows a second electrode layer 3060 that is
formed around separator layer 3050 upon performing one roll of
winding the cell stacks around the central mandrel. Electrode layer
3060 includes three negative half electrodes 3062, and three
positive half electrodes 3064, laid over the six separator half
parts 3052, in an alternating order that is a reverse of the order
in electrode layer 3040. That is, each negative half electrode 3062
is laid over a separator half part 3052 that is itself laid over a
positive half electrode 3044. Conversely, each positive half
electrode 3064 is laid over a separator half part 3052 that is
itself laid over a negative half layers 3042. Therefore, as shown
in image 3005 of FIG. 30A (assuming that the six half electrodes of
electrode layer 3060 are numbered from left to right) first, third,
and fifth half electrodes are negative half electrodes 3062; and
second, fourth, and sixth half electrodes are positive half
electrodes 3064.
[0219] Image 3005 shows two bipole electrodes that are formed via
two wirings 3066. In particular, a first bipole electrode is formed
by connecting the second and third half electrodes via wiring 3066
(which is shown and labeled in stage 3005 of FIG. 30A). Further, a
second bipole electrode is formed by connecting the fourth and
fifth half electrodes via wiring 3066 (which is shown but not
labeled in stage 3005 of FIG. 30A). The first half electrode, which
is a negative half electrode 3062, is connected to the outside from
left via a terminal wiring 3068. Further, the sixth half electrode,
which is a positive half electrode 3064, is connected to the
outside from right via another terminal wiring 3068. Electrode
layer 3060, therefore, includes from the left a negative half
electrode 3062, two bipole electrodes, and a positive half
electrode 3064.
[0220] Cell pack 3000, as shown in stage 3005 of FIG. 30A, thus
includes six cell stacks 3010 rolled around central mandrel 3020.
First, third, and fifth cell stacks each include, in order from top
to bottom, a negative half electrode 3062, a separator 3052, a
positive half electrode 3044, and another separator 3032. Further,
second, fourth, and sixth cell stacks each include, in order from
top to bottom, a positive half electrode 3064, a separator 3052, a
negative half electrode 3042, and another separator 3032. In
electrode layer 3040, first and second stacks are connected via a
wiring 3046, third and fourth stacks are connected via another
wiring 3046, and fifth and sixth stacks are connected via another
wiring 3046. In electrode layer 3060, second and third stacks are
connected via a wiring 3066, fourth and fifth stacks are connected
via another wiring 3066, and first and sixth stacks are each
connected to the outside via a terminal wiring 3068.
[0221] In some embodiments, the length of cell stacks are such that
they are wound further around the central mandrel. Each additional
rolling generates another set of cell stacks similar and on top of
those shown in FIG. 30A, image 3005.
[0222] FIG. 30B shows a path of the electron flow through cell pack
3000 according to some embodiments. The direction of electron flow
is schematically shown by arrows 3071-3077. In particular, arrows
3071 and 3077 indicate entrance and exit of electrons into cell
pack 3000, while arrows 3072-3076 depict the flow of electrons
within and among cell stacks 3010 in cell pack 300. More
specifically, arrow 3071 depicts that electrons enter the positive
half electrode 3064 of the sixth stack 3010 through the right hand
side terminal wiring 3068.
[0223] The electrons flow in each cell stack through a separator
and then flow to the neighboring cell stack through a wiring. For
example, arrow 3072 depicts that, in the sixth stack 3010, the
electrons flow from the positive half electrode 3064 through the
separator 3052 to the negative half electrode 3042, and then flow
to the positive half electrode 3044 of the fifth stack 3010 through
the wiring 3046 that connects the sixth stack to the fifth stack.
Arrow 3073, on the other hand, depicts that the electron flow
continues in the fifth stack 3010 in which the electrons flow from
the positive half electrode 3044 through the separator 3052 to the
negative half electrode 3062, and then flow to the positive half
electrode 3064 of the fourth stack 3010 through the wiring 3066
that connects the fifth stack to the fourth stack. Arrows 3074 and
3076 electron flow paths in the fourth and second stacks,
respectively, in a manner similar to that shown by arrow 3072.
Further, arrow 3075 shows an electron flow path in the third stack
in a manner similar to that shown by arrow 3073. Finally, arrow
3076 also depicts that, in the first stack, the electrons flow from
positive half electrode 3044 through separator 3052 to negative
half electrode 3062.
[0224] FIG. 31 shows a cross section of a spiral wound module 3100
according to some embodiments. As shown in FIG. 31, module 3100
includes module case 3102, case vent 3104, top cover 3106, positive
terminal 3108, negative terminal 3110, positive current collector
3112, six cylindrical cell stacks 3116, negative current collector
3120, central mandrel 3122, and bottom cover 3124. Modules 2900 or
3100 can be used in any direction and terminologies top and bottom
is used merely for referencing the figures. Each cell stack 3116 is
a cylindrical stack built by rolling flat cell stacks similar to
cell stacks 3010 in FIG. 30A. The cross section of each cell stack
3116 includes alternating layers of separators and negative or
positive half electrodes, as described above. Moreover, in some
embodiments, the outer layer of a cell stack 3116 is a separator
layer. In some embodiments, the outer separator is used, among
other things, as a reservoir for the cell electrolyte.
[0225] In some embodiments, the above-discussed design is used in
solid-state batteries, lead acid batteries, fuel cell batteries, or
some other types of electrochemical batteries. Other embodiments of
the disclosure will be apparent to those skilled in the art from
consideration of the specification and practice of the invention
disclosed herein. For example, various elements or components of
the disclosed embodiments may be combined with other elements or
components of other embodiments, as appropriate for the desired
application. Thus, it is intended that the specification and
examples be considered as exemplary only, with a true scope and
spirit of the disclosure being indicated by the following
claims.
* * * * *
References