U.S. patent application number 13/017151 was filed with the patent office on 2011-08-04 for cid retention device for li-ion cell.
This patent application is currently assigned to Boston-Power, Inc.. Invention is credited to Richard V. Chamberlain, II, Mimmo Elia, Jan-Roger B. Linna, Per Onnerud, Phillip E. Partin.
Application Number | 20110189512 13/017151 |
Document ID | / |
Family ID | 39787863 |
Filed Date | 2011-08-04 |
United States Patent
Application |
20110189512 |
Kind Code |
A1 |
Onnerud; Per ; et
al. |
August 4, 2011 |
CID Retention Device for Li-Ion Cell
Abstract
A low pressure current interrupt device (CID) activates at a
minimal threshold internal gauge pressure in a range of, for
example, between about 4 kg/cm.sup.2 and about 9 kg/cm.sup.2.
Preferably, the CID includes a first conductive plate and a second
conductive plate in electrical communication with the first
conductive plate, the electrical communication between the first
and the second conductive plates being interrupted at the minimal
threshold internal gauge pressure. More preferably, the first
conductive plate includes a frustum having a first end and a second
end, a base extending radially from a perimeter of the first end of
the frustum, and an essentially planar cap sealing the second end
of the frustum. The first end has a broader diameter than the
second end. More preferably, the second conductive plate is in
electrical contact with the essentially planar cap through a weld.
A battery, preferably a lithium-ion battery, comprises a CID as
described above. A method of manufacturing such a CID comprises
forming first and second conductive plates as described above, and
welding the second conductive plate onto the first conductive plate
while a temperature of the first conductive plate is controlled so
as not to exceed the melting point of a surface of the first
conductive plate opposite the weld.
Inventors: |
Onnerud; Per; (Framingham,
MA) ; Partin; Phillip E.; (Grafton, MA) ;
Chamberlain, II; Richard V.; (Fairfax Station, VA) ;
Linna; Jan-Roger B.; (Boston, MA) ; Elia; Mimmo;
(Belmont, MA) |
Assignee: |
Boston-Power, Inc.
Westborogh
MA
|
Family ID: |
39787863 |
Appl. No.: |
13/017151 |
Filed: |
January 31, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12623153 |
Nov 20, 2009 |
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13017151 |
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12214535 |
Jun 19, 2008 |
7838143 |
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12623153 |
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60936825 |
Jun 22, 2007 |
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Current U.S.
Class: |
429/50 ; 429/61;
73/1.71 |
Current CPC
Class: |
H01M 50/342 20210101;
H01M 50/578 20210101; Y02E 60/10 20130101; H01M 50/10 20210101;
H01M 10/0525 20130101; H01M 50/107 20210101; H01M 50/572 20210101;
Y10T 29/49108 20150115; H01M 50/103 20210101 |
Class at
Publication: |
429/50 ; 429/61;
73/1.71 |
International
Class: |
H01M 10/42 20060101
H01M010/42; G01L 27/00 20060101 G01L027/00 |
Claims
1. A pressure response device comprising: a flange portion; a
central portion, the central portion having an inlet side and an
outlet side; an angled frustum portion provided between the flange
portion and the central portion; and wherein the angled frustum
portion is configured to activate upon experiencing a predetermined
pressure differential causing the movement of the central
portion.
2. The system of claim 1, wherein upon activation, displacement of
the central portion causes the opening of an electric circuit.
3. The system of claim 1, wherein upon activation, displacement of
the central portion causes the closing of an electric circuit.
4. The device of claim 1, wherein an angle between the angled
frustum portion and a plane defined by the flange portion is
between about 10 degrees and about 60 degrees.
5. The device of claim 1, wherein an angle between the angled
frustum portion and a plane defined by the flange portion is
between about 15 degrees and about 35 degrees.
6. The device of claim 1, wherein the angled frustum portion is in
the shape of a symmetrical truncated cone.
7. The device of claim 1, wherein the angled frustum portion is in
the shape of an irregular truncated cone.
8. The device of claim 1, wherein the angled frustum portion is in
the shape of an irregular truncated dome.
9. The device of claim 1, wherein the central portion further
comprises an indentation.
10. The device of claim 9, wherein the indentation defines a cavity
in the inlet side of the central portion and wherein the
indentation defines a nipple in the outlet side of the central
portion.
11. The device of claim 9, wherein the indentation defines a cavity
in the outlet side of the central portion and wherein the
indentation defines a nipple in the inlet side of the central
portion.
12. The device of claim 1, wherein the central portion exhibits a
substantially flat shape.
13. The device of claim 1, wherein the pressure response device is
constructed from the group of materials consisting of stainless
steel, aluminum, or nickel and its alloys.
14. The device of claim 1, wherein the pressure response device is
constructed from the group of manufacturing techniques consisting
of forming or stamping metal coil, forming or stamping sheet
material, machining metal, casting, or molding.
15. A pressure response system comprising: a pressure response
device, the pressure response device including a flange portion, a
central portion, and an angled frustum portion provided between the
flange portion and the central portion; wherein the central portion
is substantially flat; a projection, the projection being operably
attached to the central portion; wherein the angled frustum portion
is configured to activate without rupturing upon experiencing a
predetermined pressure differential causing the movement of the
central portion; and wherein the activation of the frustum portion
causes the projection to indicate a pressure response.
16. A pressure response system comprising: a pressure response
device, the pressure response device including a flange portion, a
central portion, and an angled frustum portion provided between the
flange portion and the central portion, wherein the angled frustum
portion is configured to activate upon experiencing a predetermined
pressure differential causing the movement of the central portion;
a conductor, the conductor configured to make an electrical wire
connection with the central portion before the angled frustum
portion activates; and wherein the electrical wire connection is
interrupted when the angled frustum portion activates.
17. A battery device comprising: an exterior contact terminal; a
pressure response member positioned within the battery device, the
pressure response member having a first configuration and a second
configuration; the pressure response member including a central
portion surrounded by an angled frustum portion; and wherein the
pressure response member forms part of an electrical conducting
path within the battery device in the first configuration and
wherein upon experiencing a predetermined pressure condition with
the battery device, the pressure response member achieves the
second configuration and no longer forms part of an electrical
conducting path within the battery device.
18. The device of claim 17, wherein the central portion is
configured to activate without rupturing upon experiencing the
force of a predetermined pressure condition.
19. A method of testing a pressure response system comprising:
providing a pressure response member including a flange portion, a
central portion, and an angled frustum portion between the flange
portion and the central portion; applying an increasing pressure
differential to one surface of the central portion; and recording
the pressure at which the angled frustum portion activates.
20. A method of responding to an overpressure situation,
comprising: providing a pressure response member including a flange
portion, a central portion, and an angled frustum portion between
the flange portion and the central portion, wherein the pressure
response member has a first configuration and a second
configuration; exposing the pressure response member in the first
configuration to a pressure source, such that the pressure response
member responds to a predetermined pressure in the pressure source
by taking the second configuration.
21. The pressure response device of claim 1, wherein the angle
between the angled frustum portion and a plane defined by the
flange portion is bout 25 degrees.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/623,153, filed Nov. 20, 2009, which is a continuation of
U.S. application Ser. No. 12/214,535, filed Jun. 19, 2008, which
claims the benefit of U.S. Provisional Application No. 60/936,825,
filed on Jun. 22, 2007. The entire teachings of the above
applications are incorporated herein by reference.
INCORPORATION BY REFERENCE
[0002] U.S. Patent Application, filed on Jun. 22, 2007 under
Attorney's Docket No. 3853.1012-001, which is entitled "Integrated
Current-Interrupt Device For Lithium-Ion Cells"; International
Application, filed on Jun. 22, 2007 under Attorney's Docket No.
3853.1001-015, entitled "Lithium-Ion Secondary Battery"; U.S.
Provisional Application No. 60/816,775, filed Jun. 27, 2006; U.S.
Provisional Application No. 60/717,898, filed on Sep. 16, 2005;
International Application No. PCT/US2005/047383, filed on Dec. 23,
2005; U.S. patent application Ser. No. 11/474,081, filed on Jun.
23, 2006; U.S. patent application Ser. No. 11/474,056, filed on
Jun. 23, 2006; U.S. Provisional Application No. 60/816,977, filed
on Jun. 28, 2006; U.S. patent application Ser. No. 11/485,068,
filed on Jul. 12, 2006; U.S. patent application Ser. No.
11/486,970, filed on Jul. 14, 2006; U.S. Provisional Application
No. 60/852,753, filed on Oct. 19, 2006; U.S. Provisional
Application No. 61/125,327, filed on Apr. 24, 2008; U.S.
Provisional Application No. 61/125,281, filed on Apr. 24, 2008; and
U.S. Provisional Application No. 61/125,285, filed on Apr. 24, 2008
are all incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0003] Li-ion batteries in portable electronic devices typically
undergo different charging, discharging and storage routines based
on their use. Batteries that employ Li-ion cell chemistry may
produce gas when they are improperly charged, shorted or exposed to
high temperatures. This gas can be combustible and may compromise
the reliability and safety of such batteries. A current interrupt
device (CID) is typically employed to provide protection against
any excessive internal pressure increase in a battery by
interrupting the current path from the battery when pressure inside
the battery is greater than a predetermined value. The CID
typically includes first and second conductive plates in electrical
communication with each other. The first and second conductive
plates are, in turn, in electrical communication with an electrode
and a terminal of the battery, respectively. The second conductive
plate separates from (e.g., deforms away or is detached from) the
first conductive plate of the CID when pressure inside the battery
is greater than a predetermined value, whereby a current flow
between the electrode and the terminal is interrupted.
[0004] Generally, however, CIDs known in the art activate at a
relatively high pressure, for example, at an internal gauge
pressure greater than about 15 kg/cm.sup.2. Typically, when any
excessive internal pressure increase that triggers such CID
activation occurs, the internal temperature of the battery is also
relatively high, causing additional safety issues. High
temperatures are a particular concern in relatively large cells,
such as cells larger than "18650" cells (which has an outer
diameter of about 18 mm and a length of 65 mm).
[0005] Therefore, there is a need for CIDs for batteries,
particularly relatively large batteries, that can reduce or
minimize the aforementioned safety issues.
SUMMARY OF THE INVENTION
[0006] The present invention generally relates to a low pressure
CID, to a battery, such as a lithium-ion battery, comprising such a
low pressure CID, to a method of manufacturing such a low pressure
CID, and to a method of manufacturing such a battery. The CID
typically includes a first conductive plate and a second conductive
plate in electrical communication with the first conductive plate.
The electrical communication can be interrupted when a gauge
pressure between the plates is in a range of, for example, between
about 4 kg/cm.sup.2 and about 10 kg/cm.sup.2 or between about 4
kg/cm.sup.2 and about 9 kg/cm.sup.2.
[0007] In one embodiment, the present invention is directed to a
CID comprising a first conductive plate and a second conductive
plate. The first conductive plate includes a frustum having a first
end and a second end, a base extending radially from a perimeter of
the first end of the frustum, and an essentially planar cap sealing
the second end of the frustum. The first end has a broader diameter
than the second end. The second conductive plate is in electrical
contact with the essentially planar cap, preferably through a
weld.
[0008] In another embodiment, the present invention is directed to
a battery, preferably a lithium-ion battery, that includes at least
one CID as described above. The battery further includes a battery
can having a cell casing and a lid which are in electrical
communication with each other. The battery further includes a first
terminal and a second terminal. The first and second terminals are
in electrical communication with a first electrode and a second
electrode, of the battery, respectively. In the battery, the base
of the CID is proximal to the battery can, such as the cell casing
or the lid, and the essentially planar cap is distal to the cell
can. The battery can is electrically insulated from the first
terminal, and at least a portion of the battery can is at least a
component of the second terminal, or is electrically connected to
the second terminal.
[0009] In yet another embodiment, the present invention is directed
to a lithium-ion battery comprising a CID that includes a first
conductive plate and a second conductive plate. The second
conductive plate is in electrical communication with the first
conductive plate. The lithium-ion battery further includes a
battery can that includes a cell casing and a lid that are in
electrical communication with each other. The first conductive
plate of the CID is in electrical communication with the battery
can. This electrical communication is interrupted when a gauge
pressure between the plates is in a range of between about 4
kg/cm.sup.2 and about 9 kg/cm.sup.2.
[0010] The present invention also includes a method of
manufacturing a CID. The method includes the steps of forming a
first conductive plate and forming a second conductive plate. The
first conductive plate includes a frustum having a first end and a
second end, a base extending radially from a perimeter of the first
end of the frustum, and an essentially planar cap sealing the
second end. The first end of the frustum has a broader diameter
than the second end of the frustum. The method of manufacturing a
CID further includes welding the second conductive plate onto the
essentially planar cap of the first conductive plate while a
temperature of the first conductive plate is controlled so as not
to exceed the melting point of a surface of the first conductive
plate opposite the weld.
[0011] The present invention also includes a method of
manufacturing a battery of the invention as described above. The
method includes forming a CID and attaching either a first
electrode or a second electrode of the battery to the CID. The
formation of the CID includes forming a first conductive plate that
includes a frustum, having a first end and a second end having a
diameter less than that of the first end, a base extending radially
from a perimeter of the first end of the frustum, and an
essentially planar cap sealing the second end of the frustum. The
formation of the CID further includes forming a second conductive
plate, and welding the second conductive plate onto the essentially
planar cap of the first conductive plate. The welding is performed
while a temperature of the first conductive plate is controlled so
as not to exceed the melting point of a surface of the first
conductive plate opposite the weld. The method further includes
attaching the CID to a battery can including a cell casing and a
lid, i.e., either to the cell casing or to the lid. The method
further includes forming a first terminal in electrical
communication with the first electrode, and a second terminal in
electrical communication with the second electrode.
[0012] A method of manufacturing a lithium-ion battery of the
invention, as described above, is also included in the present
invention. The method includes forming a battery can that includes
a cell casing and a lid that are in electrical communication with
each other. A CID is formed. The formation of the CID includes
forming a first conductive plate, forming a second conductive
plate, and welding the second conductive plate onto the first
conductive plate while a temperature of the first conductive plate
is controlled not to exceed the melting point of a surface of the
first conductive plate opposite the weld. The weld connecting the
first conductive plate and the second conductive plate ruptures
when a gauge pressure between the first and second conductive
plates is in a range of between about 4 kg/cm.sup.2 and about 9
kg/cm.sup.2. Either a first electrode or a second electrode of the
battery to the CID is attached to the second conductive plate of
the CID. The first conductive plate of the CID is attached to a
battery can (i.e., either to the cell casing or to the lid). At
least one venting means is formed on the cell casing of the cell
can, through which gaseous species inside the battery exit when an
internal gauge pressure of the battery is in a range of between
about 12 kg/cm.sup.2 and about 20 kg/cm.sup.2. The method of
manufacturing a lithium-ion battery further includes welding the
lid onto the cell casing. The weld connecting the lid and the cell
casing ruptures when a gauge pressure between the first and second
conductive plates is equal to, or greater than, about 20
kg/cm.sup.2. In a specific embodiment, the weld connecting the lid
and the cell casing ruptures when a gauge pressure between the
first and second conductive plates is equal to, or greater than,
about 23 kg/cm.sup.2 or about 25 kg/cm.sup.2. The method of
manufacturing a lithium-ion battery further includes forming a
first terminal in electrical communication with the first
electrode, and a second terminal in electrical communication with
the second electrode.
[0013] Also includes in the present invention is a battery pack
that includes a plurality of batteries as described above.
[0014] In the batteries of the present invention, the current
interrupt device can be activated at a relatively low gauge
pressure, e.g., between about 4 kg/cm.sup.2 and about 10
kg/cm.sup.2, and interrupt internal current flow of the batteries.
Applicants have discovered that, when the low pressure CID of the
invention activates at a gauge pressure of between about 4
kg/cm.sup.2 and about 10 kg/cm.sup.2, the average cell skin
temperature in lithium-ion batteries, which have a prismatic
"183665" configuration and employ a mixture of Li.sub.1+xCoO.sub.2
(0.ltoreq.x.ltoreq.0.2) and Li.sub.1+x9Mn.sub.(2-y9)O.sub.4
(0.05.ltoreq.x9, y9.ltoreq.0.15), can be less than about 60.degree.
C. For example, during an overcharge tests of these lithium-ion
batteries at a voltage greater than about 4.2 V, the CID of the
invention activated at about between 4 kg/cm.sup.2 and about 10
kg/cm.sup.2, and the cell skin temperature at that time was in a
range of between about 50.degree. C. and about 60.degree. C. The
"183665" prismatic cell has an about 18 mm.times.36 mm prismatic
base and a length of about 65 mm, which is about twice the size of
the conventional "18650" cell. Thus, the present invention can
provide batteries, especially relatively large batteries, having
much improved safety, and battery packs including such
batteries.
[0015] In addition, the present invention can provide batteries or
battery packs that can be charged at their maximum voltage, e.g.,
4.2 V per block of series of cells, i.e., having their full
capacity. Safety concerns generally relate to a relatively high
temperature associated with the exothermic cell chemistry of the
Li.sub.1+xCoO.sub.2-based systems at a higher charging voltage.
With conventional CIDs, which generally interrupt the internal
current flow of batteries at an internal gauge pressure of about 15
kg/cm.sup.2, the cell temperature of the batteries may be excessive
before the CIDs activate and interrupt the internal current flow.
If no means of current interrupt exists, cells or batteries may
eventually vent, which can lead to an unsafe situation, because the
vented cells or batteries can expel electrolytes which can ignite
and cause fire.
[0016] The CIDs of the invention, by contrast, can provide a
solution to such problems, because they cause batteries or battery
packs, in which they are incorporated, to run at their full
capacity with lower risk than typically exists in commercially
available embodiments, since they interrupt current flow at
relatively low temperatures during overcharge. Thus, the batteries
and battery packs of the invention can employ relatively large
cells, and provide improved capacity with greater safety by
reducing likelihood of thermal runaway in the cells when they are
exposed to abuse conditions, such as an overcharge.
[0017] In some embodiments of the invention, the low pressure CID
is in electrical communication with the battery can. This design
can provide improved battery safety particularly in a battery that
does not use a crimped cap design. Batteries using crimped cap
designs (e.g. steel can cylindrical 18650s found in the market
today) often are affected by manufacturing and safety issues
surrounding the can assembly and materials, including the facts
that such cans use iron-containing materials that can corrode over
time and that the crimping process is known to be a possible source
of metal contamination in such cells. CID devices, used in such
conventional batteries, are crimped into the battery can, and are
electrically insulated from the battery can. While use of
non-crimped battery designs are known, including use of prismatic
Al cans, no CIDs have been developed for use in such cells unless
incorporated by some means of crimping. Additionally, use of
crimping methods to incorporate CIDs generally is not an efficient
utilization of space, which is one of a key design consideration
for batteries. In contrast, the present invention enables
incorporation of the low pressure CID in a non-crimped battery can
by means other than crimping, partly due to the fact that the CID
is in electrical communication with the battery can. This also
enables similar materials to be used in the construction of the CID
and the can (e.g. Al), and eliminates concerns associated with
iron-containing cans.
[0018] In some other embodiments, the present invention employs a
CID that includes a conical section, such as a frustum-shaped first
conductive plate. The frustum-shaped conductive plate can cause the
CID to activate at lower pressures than what is found in similarly
sized CID devices used today that do not employ such a frustum
shape. These lower pressures correlate to improved battery safety,
especially with regard to battery safety during an overcharge abuse
scenario. In particular, in embodiments where the frustum-shaped
first conductive plate has a planar cap sealing an end of the
frustum, and the first conductive plate is in electrical
communication with the second conductive plate at the planar cap,
the planar cap enables the two plates to be welded to each other.
Use of suitable welding technique can enable, at least in part,
improved control of activation pressure of batteries employing CIDs
of the invention, for example, by controlling the position or the
number of welding. Also, the CID, employing the frustum-shaped
conductive plate, can provide the current interrupt function and
occupy a significantly reduced amount of space within the battery,
both in terms of overall height and cross-section, so that more
space can be used for materials directly related to power
generating aspects of the battery. In addition, the invention
allows manufacturing of a CID device in an efficient process with
consideration to time, cost and quality. Particularly with regards
to quality, the frustum-shape enables the CID device of the
invention to achieve pressure activation in a narrow range and
therefore allows better battery design of the battery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view of a CID of the invention.
[0020] FIGS. 2A-2C show one embodiment of a first conductive plate
of the CID of FIG. 1, wherein FIG. 2A shows a side view of the
first conductive plate, FIG. 2B shows a top view of the first
conductive plate, and FIG. 2C shows a cross-sectional view of the
first conductive plate along line A-A of FIG. 2B.
[0021] FIGS. 3A-3C show one embodiment of a second conductive plate
of the CID of FIG. 1, wherein FIG. 3A shows a plane view of the
second conductive plate, FIG. 3B shows a perspective view of the
second conductive plate, and FIG. 3C shows a cross-sectional view
of the second conductive plate along line A-A of FIG. 3A.
[0022] FIG. 4 show one embodiment of an end plate which can house
the CID of FIG. 1.
[0023] FIGS. 5A-5C show one embodiment of a retainer disposed
between a portion of a first conductive plate and a portion of a
second conductive plate, of the CID of FIG. 1, wherein an insulator
component of the retainer is shown in FIG. 5A, a side view of a
ring component of the retainer is shown in FIG. 5B, and a top view
of the ring of the retainer is shown in FIG. 5C.
[0024] FIGS. 6A and 6B show one embodiment of the CID of the
invention, wherein FIG. 6A shows an assembly of a first conductive
plate, a second conductive plate and a retainer between them onto
an end plate, and FIG. 6B shows the assembled CID.
[0025] FIGS. 7A and 7B show another embodiment of the CID of the
invention, wherein FIG. 7A shows an assembly of a first conductive
plate, a second conductive plate and a retainer between them onto
an end plate, and FIG. 7B shows the assembled CID.
[0026] FIG. 8A shows one embodiment in a prismatic format of the
battery of the invention.
[0027] FIG. 8B shows a bottom view of a lid portion of the battery
of FIG. 8A, taken from the inside of the battery.
[0028] FIG. 8C shows a cross sectional view of the lid portion of
FIG. 8B along the line A-A.
[0029] FIG. 8D shows one embodiment of a cylindrical format of the
battery of the invention.
[0030] FIG. 8E shows a side view of the bottom can portion of the
battery of FIG. 8D from inside of the battery.
[0031] FIG. 8F shows a side view of the top lid portion of the
battery of FIG. 8E from inside of the battery.
[0032] FIG. 9 is a schematic circuitry showing how individual cells
in the invention are preferably connected when arranged together in
a battery pack of the invention.
[0033] FIG. 10 is a graph showing CID trip pressures of the CIDs of
the invention.
[0034] FIG. 11 is a graph showing pressure rise rates with respect
to overcharging voltages of the batteries of the invention, when
the batteries were overcharged at a 2 C rate per minute.
[0035] FIG. 12 is a graph showing cell skin temperatures of the
batteries of the invention measured when their CIDs were
activated.
[0036] FIG. 13 is a graph showing the maximum cell skin
temperatures of batteries of the invention that were overcharged at
a 2 C rate per minute.
[0037] FIG. 14 is a graph showing calculated pressures versus the
measured cell skin temperatures of a battery of the invention that
was overcharged at a 2 C rate per minute.
[0038] FIG. 15 is a graph showing cell skin temperatures of the
batteries of the invention with CIDs of the invention (curves A and
B) and control batteries with conventional CIDs (curves C and
D).
DETAILED DESCRIPTION OF THE INVENTION
[0039] The foregoing will be apparent from the following more
particular description of example embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating embodiments of the present invention.
[0040] As used herein, the "terminals" of the batteries of the
invention mean the parts or surfaces of the batteries to which
external electric circuits are connected.
[0041] The batteries of the invention typically include a first
terminal in electrical communication with a first electrode, and a
second terminal in electrical communication with a second
electrode. The first and second electrodes are contained within the
cell casing of a battery of the invention, for example, in a "jelly
roll" form. The first terminal can be either a positive terminal in
electrical communication with a positive electrode of the battery,
or a negative terminal in electrical communication with a negative
electrode of the battery, and vice versa for the second terminal.
Preferably, the first terminal is a negative terminal in electrical
communication with a negative electrode of the battery, and the
second terminal is a positive terminal in electrical communication
with a positive electrode of the battery.
[0042] As used herein, the phrase "electrically connected" or "in
electrical communication" or "electrically contacted" means certain
parts are in communication with each other by flow of electrons
through conductors, as opposed to electrochemical communication
which involves flow of ions, such as Li.sup.+, through
electrolytes.
[0043] The CID of the battery of the invention can active at an
internal gauge pressure in a range of, for example, between about 4
kg/cm.sup.2 and about 10 kg/cm.sup.2, such as between about 4
kg/cm.sup.2 and about 9 kg/cm.sup.2, between about 5 kg/cm.sup.2
and about 9 kg/cm.sup.2 or 7 kg/cm.sup.2 and about 9 kg/cm.sup.2.
As used herein, "activation" of the CID means that current flow of
an electronic device through the CID is interrupted. In a specific
embodiment, the CID of the invention includes a first conductive
plate and a second conductive plate in electrical communication
with each other (e.g., by welding, crimping, riveting, etc.). In
this CID, "activation" of the CID means that the electrical
communication between the first and second conductive plates is
interrupted. Preferably, when the second conductive plate separates
from (e.g., deforms away or is detached from) the first conductive
plate, no rupture occurs in the first conductive plate.
[0044] In some embodiments, the CID of the battery of the
invention, which employs a first conductive plate and a second
conductive plate that is in electrical communication with, and
pressure (i.e., fluid such as gas) communication with, the first
conductive plate and with the battery can of the battery, activates
at an internal gauge pressure in a range of, for example, between
about 4 kg/cm.sup.2 and about 9 kg/cm.sup.2, such as between about
5 kg/cm.sup.2 and about 9 kg/cm.sup.2 or 7 kg/cm.sup.2 and about 9
kg/cm.sup.2. In these embodiments, preferably, the first conductive
plate includes a cone- or dome-shaped part. More preferably, at
least a portion of the top (or cap) of the cone- or dome-shaped
part is essentially planar. Preferably, the first and second
conductive plates are in direct contact with each other at a
portion of the essentially planar cap. More preferably, the first
conductive plate includes a frustum having an essentially planar
cap.
[0045] FIG. 1 shows one specific embodiment of the CID of the
invention. CID 10 shown in FIG. 1 includes first conductive plate
12 and second conductive plate 24. As shown in FIGS. 2A-2C, first
conductive plate 12 includes frustum 14 that includes first end 16
and second end 18. First end 16 has a broader diameter than second
end 18. First conductive plate 12 also includes base 20 extending
radially from a perimeter of first end 16 of frustum 14.
Essentially planar cap 22 seals second end 18 of frustum 14. As
used herein, the term "frustum" means the basal wall part
(excluding the bottom and top ends) of a solid right circular cone
(i.e., solid generated by rotating a right triangle about one of
its legs) by cutting off the top intersected between two parallel
planes.
[0046] As used herein, the term "essentially planar cap" means a
planar cap which includes a surface that sufficiently resembles a
plane to potentially contact a planar surface randomly at more than
one point and whereby the planar cap and the planar surface can be
fused by a suitable means, such as by spot welding. In some
embodiments, deformation of the essentially planar cap caused by
assembly or by fabrication of the first conductive plate having the
essentially planar cap to form CID 10 (e.g., by welding of first
conductive plate 12 to second conductive plate 24) is considered to
be essentially planar.
[0047] Preferably, flat cap 22 and/or base 20 has a thickness
(indicated with reference character "d" in FIG. 2C) in a range of
between about 0.05 millimeters and about 0.5 millimeters, such as
between about 0.05 millimeters and about 0.3 millimeters, between
about 0.05 millimeters and 0.2 millimeters, between about 0.05
millimeters and about 0.15 millimeters (e.g., about 0.127
millimeter (or about 5 milli-inch)).
[0048] Preferably, the diameter of flat cap 22 (indicated with
reference character "b" in FIG. 2C) is in a range of between about
2 millimeters and about 10 millimeters, more preferably between 5
millimeters and about 10 millimeters, even more preferably between
about 5 millimeters and 8 millimeters (e.g., between about 0.20
inches and 0.25 inches), such as about 5.5 millimeter (or about
0.215 inch).
[0049] Preferably, the height of essentially planar cap 22 from
base 20 (indicated with reference character "c" in FIG. 2C) is in a
range of between about 0.5 millimeter and about 1 millimeter, more
preferably between about 0.6 millimeter and about 0.8 millimeter,
such as about 0.762 millimeter (or about 0.315 inch).
[0050] Preferably, frustum 14 has an angle relative to a plane
parallel to base 20 in a range of between about 15 degrees and
about 25 degrees, such as between about 18 degrees and about 23
degrees, or between about 19 degrees and about 21 degrees. More
preferably, frustum 14 has an angle of about 21 degrees relative to
a plane parallel to base 20. Preferably, frustum 14 has a diameter
ratio of first end 16 to second end 18 (i.e., ratio of "b" to "a"
in FIG. 2C) in a range of between about 1:1.20 and about 1:1.35,
such as between about 1:1.23 and about 1:1.28.
[0051] Second conductive plate 24 is in electrical and pressure
(i.e., fluid such as gas) communication with first conductive plate
12. Preferably, second conductive plate 24 defines at least one
opening 26 through which first conductive plate 12 and second
conductive plate 24 are in pressure communication with each other.
One embodiment of such second conductive plate 24 is shown in FIGS.
3A-3C. As shown in FIGS. 3A and 3B, second conductive plate 24
defines at least one opening 26 through which first conductive
plate 12 and second conductive plate 24 are in pressure (e.g., gas)
communication with each other. Preferably, second conductive plate
24 includes embossment (or depression) 28, and, thus, has flat side
30 and depression side 32 (FIG. 3C). Referring back to FIG. 1, flat
side 30 of second conductive plate 24 faces toward first conductive
plate 12. Second conductive plate 24 is in electrical contact with
essentially planar cap 22 of first conductive plate 12, preferably
through a weld. Preferably, the weld connecting essentially planar
cap 22 of first conductive plate 12 and second conductive plate 24
is at flat side 30 at depression 28. Preferably, the weld is at
least one spot weld, such as one, two, three or four. More
preferably, at least one of the spot welds includes aluminum. Even
more preferably, the weld is two spot welds. Preferably, the two
spot welds are separated from each other.
[0052] Any suitable welding technique known in the art can be used
to weld first and second conductive plates 12 and 24. Preferably, a
laser welding technique is employed in the invention. More
preferably, during the welding process (e.g., laser welding
process), a temperature of first conductive plate 12 is controlled
so as not to exceed the melting point of a surface of the first
conductive plate opposite the weld. Such controlling can be done
using any suitable cooling methods known in the art. Preferably,
the thickness of second conductive plate 24 proximate to the weld
with first conductive plate 12 is equal to or greater than one-half
of the thickness of first conductive plate 12 proximate to the
weld, but less than the thickness of the first conductive plate
proximate to the weld.
[0053] Referring back to FIG. 1, CID 10 optionally includes end
plate 34. One particular embodiment of end plate 34 is shown in
FIG. 4. End plate 34 includes first recess 36 and second recess 38.
The diameter of first recess 36 (indicated with reference character
"a" in FIG. 4) is preferably co-terminus with the outer diameter of
base 20 of first conductive plate 12 (as shown in FIG. 1). As used
herein, the "co-terminus" means that the diameter of first recess
36 is essentially the same as, or slightly larger than the outer
diameter of base 20 of first conductive plate 12 by between about
101% and about 120% (e.g., about 110%). The depth of first recess
36 (indicated with reference character "b" in FIG. 4) is slightly
less, for example, about 90% less, than the thickness of base 20 of
first conductive plate 12 (indicated with reference character "d"
in FIG. 2C). Second recess 38 can accommodate frustum 14 of first
conductive plate 12 upon its reversal. This second recess 38 is
preferably co-terminus with the perimeter of first end 16 of
frustum 14 of first conductive plate 12 (as shown in FIG. 1). As
used herein, the "co-terminus" means that the diameter (indicated
with reference character "c" in FIG. 4) of second recess 38 is
essentially the same as, or slightly larger than that of cap 22 of
frusturm 14, by between about 101% and about 120% (e.g., about
103%). The depth of second recess 38 (indicated with reference
character "d" in FIG. 4), as measured from first recess 36, is
slightly larger, for example, between about 110% and about 130%
(e.g., about 125%) larger, than the height of first conductive
plate 12 (indicated with reference character "c" in FIG. 2C).
[0054] As shown in FIG. 1, first conductive plate 12 and end plate
34 are in electrical contact with each other. This electrical
contact can be made by any suitable method known in the art, for
example, by welding, crimping, riveting, etc. Preferably, first
conductive plate 12 and end plate 34 are welded to each other. Any
suitable welding technique known in the art can be used.
Preferably, first conductive plate 12 and end plate 34 are
hermetically joined. Preferably, a laser welding techniques is
employed in the invention. More preferably, a circumferential laser
welding technique is used to hermetically join first conductive
plate 12 and end plate 34, for example, either by means of seam
welding at the circumferential interface between the two parts or
by means of penetration welding at base 20 of first conductive
plate 12. Preferably, the welding is circumferentially placed
around the middle of base 20 or the edge of base 20 (indicated with
reference characters "a" and "b," respectively, in FIG. 1).
Preferably, during the welding process (e.g., laser welding
process), a temperature of first conductive plate 12 is controlled
so as not to exceed the melting point of a surface of the first
conductive plate opposite the weld. Such temperature control can be
obtained using any suitable cooling method known in the art.
[0055] First conductive plate 12, second conductive plate 24 and
end plate 34 can be made of any suitable conductive material known
in the art for a battery. Examples of suitable materials include
aluminum, nickel and copper, preferably aluminum, such as Aluminum
3003 series (e.g., Aluminum 3003 H-14 series for second conductive
plate 24 and end plate 34, and Aluminum 3003 H-0 series for first
conductive plate 12). Preferably, first conductive plate 12 and
second conductive plate 24 are made of substantially the same
metals. More preferably, first conductive plate 12, second
conductive plate 24 and end plate 36 are made of substantially the
same metals. As used herein, the term "substantially same metals"
means metals that have substantially the same chemical and
electrochemical stability at a given voltage, e.g., the operation
voltage of a battery. In one specific embodiment, at least one of
first conductive plate 12 and second conductive plate 24 includes
aluminum, such as Aluminum 3003 series. In one more specific
embodiment, first conductive plate 12 includes aluminum which is
softer than that of second conductive plate. Preferably, first
conductive plate 12 and second conductive plate 24 both include
aluminum. Even more preferably, first conductive plate 12, second
conductive plate 24 and end plate 36 all include aluminum, such as
Aluminum 3003 series.
[0056] Frustum 14 and flat cap 22 of first conductive plate 12,
embossment 28 of second conductive plate 24 and recesses 36 and 38
of end plate 34 can be made by any suitable method known in the
art, for example, by stamping, coining, and/or milling
techniques.
[0057] Referring back to FIG. 1, in a preferred embodiment, the CID
of the invention further includes retainer 40 (e.g., electrically
insulating layer, ring or gasket) between a portion of first
conductive plate 12 and a portion of second conductive plate 24.
Retainer 40, such as an electrically insulating ring, extends about
the perimeter of frustum 14, and between base 20 of first
conductive plate 12 and second conductive plate 24.
[0058] One specific embodiment of retainer 40 is shown in FIGS.
5A-5C, and FIGS. 6A and 6B. Retainer 40 of FIGS. 5A-5C, and FIGS.
6A and 6B includes an insulator 42, such as an electrically
insulating ring, which defines at least two grooves 43, 45 about a
perimeter of the insulator 42. Retainer 40 further includes ring
44, such as a metal ring, having tabs 46. As shown in FIGS. 6A and
6B, ring 44 can rest inside groove 45 and second conductive plate
24 can rest inside groove 43. Tabs 46 can be maleably adjusted and
secured to a metal surface of lid 106 (or a surface of an end plate
which is a part of the lid), on which first conductive plate 12 is
resting, thereby securing ring 44 over first conductive plate 12.
As shown in FIGS. 5A and 5B, and 6A and 6B, the number of tabs 46
can be any number, for example, one, two, three or four.
[0059] Another specific embodiment of retainer 40 is shown in FIGS.
7A and 7B. Retainer 40 of FIGS. 7A and 7B is an insulator, such as
an electrically insulating ring, that defines at least one opening
48 and groove 50 about a perimeter of retainer 40. As shown in FIG.
7A, second conductive plate 24 can rest inside groove 50. In this
embodiment, first conductive plate 12 preferably includes at least
one tab 52. Tabs 52 of first conductive plate 12, and opening 48 of
retainer 40 are capable of alignment when retainer 40 and base 22
of first conductive plate 12 are concentric. Tabs 52 of first
conductive plate 12 can be maleably adjusted to secure retainer 40
to first conductive plate 12, as shown in FIG. 7B.
[0060] The CIDs of the invention, such as CID 10, can be included
in a battery, such as a lithium-ion battery. FIGS. 8A and 8D show
two different embodiments of battery 100 (which is collectively
referred to for battery 100A of FIG. 8A and battery 100B of FIG.
8D) of the battery of the invention. FIG. 8B shows a bottom view of
a lid portion of battery 100, including CID 10, when it is seen
from the inside of the battery. FIGS. 8C and 8F show a
cross-sectional view of the lid portion, of battery 100A of FIG. 8A
and, of battery 100B of FIG. 8D, respectively.
[0061] As shown in FIGS. 8A-8F, battery 100 includes CID 10,
battery can 102 that includes cell casing 104 and lid 106, first
electrode 108 and second electrode 110. First electrode 108 is in
electrical communication with a first terminal of the battery, and
second electrode 110 is in electrical communication with a second
terminal of the battery. The cell casing 104 and lid 106 are in
electrical contact with each other. The tabs (not shown in FIG. 8A
and FIG. 8D) of first electrode 108 are electrically connected
(e.g., by welding, crimping, riveting, etc.) to
electrically-conductive, first component 116 of feed-through device
114. The tabs (not shown in FIG. 8A and FIG. 8D) of second
electrode 110 are in electrically connected (e.g., by welding,
crimping, riveting, etc.) to second conductive plate 24 of CID
10.
[0062] Features of CID 10, including preferred features, are as
described above. Specifically, in FIGS. 8A-8C and FIGS. 8D-8F, CID
10 includes first conductive plate 12, second conductive plate 24,
end plate 34 and retainer 40. As shown in FIG. 8A and FIG. 8D, in
battery 100, end plate 34 is a part of lid 106 of cell can 102.
Although not shown, separate end plate 34 can be used in the
invention. Features, including preferred features, of first
conductive plate 12, second conductive plate 24, retainer 40 and
end plate 34 are as described above. Preferably, when second
conductive plate 24 separates from first conductive plate 12, no
rupture occurs in second conductive plate 24 so that gas inside
battery 100 does not go out through second conductive plate 24. The
gas can exit battery 100 through one or more venting means 112 (see
FIG. 8A and FIG. 8D) at cell casing 104, which will be discussed
later in detail, when the pressure keeps increasing and reaches a
predetermined value for activation of venting means 112. In some
embodiments, the predetermined value for activation of venting
means 112, which is, for example, an internal gauge pressure in a
range of between about 10 kg/cm.sup.2 and about 20 kg/cm.sup.2,
such as between about 12 kg/cm.sup.2 and about 20 kg/cm.sup.2, is
higher than that for the activation of CID 10, for example, between
about 4 kg/cm.sup.2 and about 10 kg/cm.sup.2 or between about 4
kg/cm.sup.2 and about 9 kg/cm.sup.2. This feature helps prevent
premature gas leakage, which can damage neighboring batteries (or
cells) which are operating normally. So, when one of a plurality of
cells in the battery packs of the invention is damaged, the other
healthy cells are not damaged. It is noted that gauge pressure
values or sub-ranges suitable for the activation of CID 10 and
those for activation of venting means 112 are selected from among
the predetermined gauge pressure ranges such that there is no
overlap between the selected pressure values or sub-ranges.
Preferably, the values or ranges of gauge pressure for the
activation of CID 10 and those for the activation of venting means
112 differ by at least about 2 kg/cm.sup.2, more preferably by at
least about 4 kg/cm.sup.2, even more preferably by at least about 6
kg/cm.sup.2, such as by about 7 kg/cm.sup.2.
[0063] CID 10 can be made as described above. Attachment of CID 10
to battery can 102 of battery 100 can be done by any suitable means
known in the art. Preferably, CID 10 is attached to battery can 102
via welding, and more preferably by welding first conductive plate
12 onto end plate 34 of lid 106, as described above for the CID of
the invention.
[0064] Although one CID 10 is employed in battery 100, more than
one CID 10 can be employed in the invention. Also, although in
FIGS. 8A-8C and FIGS. 8D-8F, CID 10 in electrical contact with
second electrode 110 is depicted, in some other embodiments, CID 10
can be in electrical communication with first electrode 108 and
feed-through device 114 that is insulated from cell can 102, and
second electrode 110 is directly in electrical contact with cell
can 102. In such embodiments, CID 10 is not in electrical
communication with cell can 102. Also, although in FIGS. 8A-8C and
FIGS. 8E-8F, CID 10 is depicted to be positioned at inside 105 of
lid 106 (see FIG. 8C and FIG. 8F), CID 10 of the invention can be
placed at any suitable place of battery 100, for example, on the
side of cell casing 102 or top side 107 of lid 106.
[0065] As shown in FIG. 8C and FIG. 8E, feed-through device 114
includes first conductive component 116, which is electrically
conductive, insulator 118, and second conductive component 120,
which can be the first terminal of battery 100. As used herein, the
term "feed-through" includes any material or device that connects
an electrode of a battery within a space defined by a casing and
lid of a battery, with a component of the battery external to that
defined internal space. Preferably, the feed-through material or
device extends through a pass-through hole defined by a lid of the
battery. Feed-through device 114 can pass through a lid of a cell
casing of a battery without deformation, such as by bending,
twisting and/or folding of electrode tabs, and, thus, can increase
cell capacity. Such a feed-through device can potentially increase
(e.g., 5-15%) cell capacity due to increased volume utilization, as
compared to that of a conventional lithium battery in which
current-carrying tabs are folded or bent into a cell casing and are
welded with internal electrodes. First and second conductive
components, 116, 120, can be made of any suitable electrically
conductive material, such as nickel. Any suitable insulating
materials known in the art can be used for insulator 118.
[0066] Cell casing 104 can be made of any suitable conductive
material which is essentially stable electrically and chemically at
a given voltage of batteries, such as the lithium-ion batteries of
the invention. Examples of suitable materials of cell casing 104
include aluminum, nickel, copper, steel, nickel-plated iron,
stainless steel and combinations thereof. Preferably, cell casing
104 is of, or includes, aluminum. Examples of suitable materials of
lid 106 are the same as those listed for cell casing 104.
Preferably lid 106 is made of the same material as cell casing 104.
In a more preferred embodiment, both cell casing 104 and lid 106
are formed of, or include, aluminum. Lid 106 can hermetically seal
cell casing 104 by any suitable method known in the art (e.g.,
welding, crimping, etc). Preferably, lid 106 and cell casing 104
are welded to each other. Preferably, the weld connecting lid 106
and cell casing 104 ruptures when an gauge pressure between lid 106
and cell casing 104 is greater than about 20 kg/cm.sup.2.
[0067] In a preferred embodiment of the battery of the invention,
at least one of cell casing 104 and lid 106 of battery can 102 are
in electrical communication with second electrode 110 of battery
100 through CID 108, as shown in FIG. 8A and FIG. 8D. Battery can
102 is electrically insulated from first terminal 120, and at least
a portion of cell can 102 is at least a component of a second
terminal of battery 100, or is electrically connected to the second
terminal. In a more preferred embodiment, at least a portion of lid
106 or the bottom end of cell casing 104, serves as the second
terminal.
[0068] As shown in FIG. 8C and FIG. 8F, at least a portion of
battery can 102, e.g., lid 106 or the bottom end of cell casing
104, can be the second terminal of battery 100. Alternatively, at
least a portion of battery can 102 can be at least a component of
the second terminal, or electrically connected to the second
terminal. Lid 106 of cell can 102 is electrically insulated from
feed-through device 114 by insulator 118, such as an insulating
gasket or ring. The insulator is formed of a suitable insulating
material, such as polypropylene, polyvinylfluoride (PVF), natural
polypropylene, etc. Preferably, the first terminal is a negative
terminal, and the second terminal of battery 100, which is in
electrical communication with cell can 102, is a positive
terminal.
[0069] Referring back to FIG. 8A and FIG. 8D, in some preferred
embodiments, cell casing 104 includes at least one venting means
112 as a means for venting interior gaseous species when necessary,
such as when gas within lithium ion battery 100 is greater than a
value, for example, an internal gauge pressure in a range of
between about 10 kg/cm.sup.2and about 20 kg/cm.sup.2, such as
between about 12 kg/cm.sup.2 and about 20 kg/cm.sup.2 or between
about 10 kg/cm.sup.2and about 18 kg/cm.sup.2. It is to be
understood that any suitable type of venting means can be employed
as long as the means provide hermetic sealing in normal battery
operation conditions. Various suitable examples of venting means
are described in U.S. Provisional Application No. 60/717,898, filed
on Sep. 16, 2005, the entire teachings of which are incorporated
herein by reference.
[0070] Specific examples of venting means include vent scores. As
used herein, the term "score" means partial incision of section(s)
of a cell casing, such as cell casing 104, that is designed to
allow the cell pressure and any internal cell components to be
released at a defined internal pressure. Preferably, venting means
112 is a vent score, more preferably, vent score that is
directionally positioned away from a user/or neighboring cells.
More than one vent score can be employed in the invention. In some
embodiments, patterned vent scores can be employed. The vent scores
can be parallel, perpendicular, diagonal to a major stretching (or
drawing) direction of the cell casing material during creation of
the shape of the cell casing. Consideration is also given to vent
score properties, such as depth, shape and length (size).
[0071] The batteries of the invention can further include a
positive thermal coefficient layer (PTC) in electrical
communication with either the first terminal or the second
terminal, preferably in electrical communication with the first
terminal. Suitable PTC materials are those known in the art.
Generally, suitable PTC materials are those that, when exposed to
an electrical current in excess of a design threshold, its
electrical conductivity decreases with increasing temperature by
several orders of magnitude (e.g., 10.sup.4 to 10.sup.6 or more).
Once the electrical current is reduced below a suitable threshold,
in general, the PTC material substantially returns to the initial
electrical resistivity. In one suitable embodiment, the PTC
material includes small quantities of semiconductor material in a
polycrystalline ceramic, or a slice of plastic or polymer with
carbon grains embedded in it. When the temperature of the PTC
material reaches a critical point, the semiconductor material or
the plastic or polymer with embedded carbon grains forms a barrier
to the flow of electricity and causes electrical resistance to
increase precipitously. The temperature at which electrical
resistivity precipitously increases can be varied by adjusting the
composition of the PTC material, as is known in the art. An
"operating temperature" of the PTC material is a temperature at
which the PTC exhibits an electrical resistivity about half way
between its highest and lowest electrical resistance. Preferably,
the operating temperature of the PTC layer employed in the
invention is between about 70.degree. Celsius and about 150.degree.
Celsius.
[0072] Examples of specific PTC materials include polycrystalline
ceramics containing small quantities of barium titanate
(BaTiO.sub.3), and polyolefins including carbon grains embedded
therein. Examples of commercially available PTC laminates that
include a PTC layer sandwiched between two conducting metal layers
include LTP and LR4 series manufactured by Raychem Co. Generally,
the PTC layer has a thickness in a range of about 50 .mu.m and
about 300 .mu.m.
[0073] Preferably, the PTC layer includes electrically conductive
surface, the total area of which is at least about 25% or at least
about 50% (e.g., about 48% or about 56%) of the total surface area
of lid 106 or the bottom of battery 100. The total surface area of
the electrically conductive surface of the PTC layer can be at
least about 56% of the total surface area of lid 106 or the bottom
of battery 100. Up to 100% of the total surface area of lid 106 of
battery 100 can be occupied by the electrically conductive surface
of the PTC layer. Alternatively, the whole, or part, of the bottom
of battery 100 can be occupied by the electrically conductive
surface of the PTC layer.
[0074] The PTC layer can be positioned externally to the battery
can, for example, over a lid of the battery can.
[0075] In a preferred embodiment, the PTC layer is between a first
conductive layer and a second conductive layer and at least a
portion of the second conductive layer is at least a component of
the first terminal, or is electrically connected to the first
terminal. In a more preferred embodiment, the first conductive
layer is connected to the feed-through device. Suitable examples of
such a PTC layer sandwiched between the first and second conductive
layers are described in U.S. patent application Ser. No.
11/474,081, filed on Jun. 23, 2006, the entire teachings of which
are incorporated herein by reference.
[0076] In a preferred embodiment, the battery of the invention
includes battery can 102 that includes cell casing 104 and lid 106,
at least one CID, preferably CID 10 as described above, in
electrical communication with either of the first or second
electrodes of the battery, and at least one venting means 112 on
cell casing 104. As described above, battery can 102 is
electrically insulated from the first terminal that is in
electrical communication with the first electrode of the battery.
At least a portion of battery can 102 is at least a component of
the second terminal that is in electrical communication with the
second electrode of the battery. Lid 106 is welded on cell casing
104 such that the welded lid is detached from cell casing 104 at an
internal gauge pressure greater than about 20 kg/cm.sup.2. The CID
includes a first conductive plate (e.g., first conductive plate 12)
and a second conductive plate (e.g., second conductive plate 24) in
electrical communication with each other, preferably by a weld.
This electrical communication is interrupted at an internal gauge
pressure between about 4 kg/cm.sup.2 and about 9 kg/cm.sup.2,
between about 5 kg/cm.sup.2 and about 9 kg/cm.sup.2 or between
about 7 kg/cm.sup.2 and about 9 kg/cm.sup.2. For example, the first
and second conductive plates are welded, e.g., laser welded, to
each other such that the weld ruptures at the predetermined gauge
pressure. At least one venting means 112 is formed to vent interior
gaseous species when an internal gauge pressure in a range of
between about 10 kg/cm.sup.2and about 20 kg/cm.sup.2 or between
about 12 kg/cm.sup.2and about 20 kg/cm.sup.2. As described above,
it is noted that gauge pressure values or sub-ranges suitable for
the activation of CID 10 and those for activation of venting means
112 are selected from among the predetermined gauge pressure ranges
such that there is no overlap between the selected pressure values
or sub-ranges. Preferably, the values or ranges of gauge pressure
for the activation of CID 10 and those for the activation of
venting means 112 differ by at least about 2 kg/cm.sup.2 pressure
difference, more preferably by at least about 4 kg/cm.sup.2, even
more preferably by at least about 6 kg/cm.sup.2, such as by about 7
kg/cm.sup.2. Also, it is noted that gauge pressure values or
sub-ranges suitable for the rupture of the welded lid 106 from cell
casing 104 and those for activation of venting means 112 are
selected from among the predetermined gauge pressure ranges such
that there is no overlap between the selected pressure values or
sub-ranges. Preferably, the values or ranges of gauge pressure for
the activation of CID 10 and those for the activation of venting
means 112 differ by at least about 2 kg/cm.sup.2 pressure
difference, more preferably by at least about 4 kg/cm.sup.2, even
more preferably by at least about 6 kg/cm.sup.2.
[0077] Preferably, the battery of the invention is rechargeable,
such as a rechargeable lithium-ion battery.
[0078] Preferably, the battery of the invention, such as a
lithium-ion battery, has an internal gauge pressure of less than or
equal to about 2 kg/cm.sup.2 under a normal working condition. For
such a battery of the invention, in one embodiment, the active
electrode materials are first activated and then the battery can of
the battery is hermetically sealed.
[0079] The battery (or cell) of the invention can be cylindrical
(e.g., 26650, 18650, or 14500 configuration) or prismatic (stacked
or wound, e.g., 183665 or 103450 configuration). Preferably, they
are prismatic, and, more preferably, of a prismatic shape that is
oblong. Although the present invention can use all types of
prismatic cell casings, an oblong cell casing is preferred partly
due to the two features described below.
[0080] The available internal volume of an oblong shape, such as
the 183665 form factor, is larger than the volume of two 18650
cells, when comparing stacks of the same external volume. When
assembled into a battery pack, the oblong cell fully utilizes more
of the space that is occupied by the battery pack. This enables
novel design changes to the internal cell components that can
increase key performance features without sacrificing cell capacity
relative to that found in the industry today. Due to the larger
available volume, one can elect to use thinner electrodes, which
have relatively higher cycle life and a higher rate capability.
Furthermore, an oblong can has larger flexibility. For instance, an
oblong shape can flex more at the waist point compared to a
cylindrically shaped can, which allows less flexibility as stack
pressure increases upon charging. The increased flexibility
decreases mechanical fatigue on the electrodes, which, in turn,
causes higher cycle life. Also, clogging of pores of a separator in
batteries can be improved by a relatively low stack pressure.
[0081] A particularly desired feature, allowing relatively higher
safety, is available for the oblong shaped battery compared to the
prismatic battery. The oblong shape provides a snug fit to the
jelly roll, which minimizes the amount of electrolyte necessary for
the battery. The relatively low amount of electrolyte results in
less available reactive material during a misuse scenario and hence
higher safety. In addition, cost is lower due to a lower amount of
electrolyte. In the case of a prismatic can with a stacked
electrode structure, whose cross-section is in a rectangular shape,
essentially full volume utilization is possible without unnecessary
electrolyte, but this type of can design is more difficult and
hence more costly from a manufacturing point-of-view.
[0082] Referring to FIG. 9, in some embodiments of the invention, a
plurality of lithium-ion batteries of the invention (e.g., 2 to 5
cells) can be connected in a battery pack, wherein each of the
batteries (cells) is connected with each other in series, parallel,
or in series and parallel. In some battery packs of the invention,
there are no parallel connections between the batteries.
[0083] Preferably, at least one cell has a prismatic shaped cell
casing, and more preferably, an oblong shaped cell casing, as shown
in FIG. 8A. Preferably, the capacity of the cells in the battery
pack is typically equal to or greater than about 3.0 Ah, more
preferably equal to or greater than about 4.0 Ah. The internal
impedance of the cells is preferably less than about 50 milli-ohms,
and more preferably less than 30 milli-ohms.
[0084] The lithium-ion batteries and battery packs of the invention
can be used for portable power devices, such as portable computers,
power tools, toys, portable phones, camcorders, PDAs and the like.
In portable electronic devices using lithium-ion batteries, their
charges are, in general, designed for a 4.20 V charging voltage.
Thus, the lithium-ion batteries and battery packs of the invention
are particularly useful for these portable electronic devices.
[0085] The present invention also includes methods of producing a
battery, such as a lithium-ion battery, as described above. The
methods include forming a cell casing as described above, and
disposing a first electrode and a second electrode within the cell
casing. A current interrupt device, as described above (e.g.,
current interrupt device 28), is formed and electrically connected
with the cell casing.
[0086] Positive and negative electrodes and electrolytes for the
lithium-ion batteries of the invention can be formed by suitable
methods known in the art.
[0087] Examples of suitable negative-active materials for the
negative electrodes include any material allowing lithium to be
doped or undoped in or from the material. Examples of such
materials include carbonaceous materials, for example,
non-graphitic carbon, artificial carbon, artificial graphite,
natural graphite, pyrolytic carbons, cokes such as pitch coke,
needle coke, petroleum coke, graphite, vitreous carbons, or a
heat-treated organic polymer compounds obtained by carbonizing
phenol resins, furan resins, or similar, carbon fibers, and
activated carbon. Further, metallic lithium, lithium alloys, and an
alloy or compound thereof are usable as the negative active
materials. In particular, the metal element or semiconductor
element allowed to form an alloy or compound with lithium may be a
group IV metal element or semiconductor element, such as, but not
limited to, silicon or tin. In particular, amorphous tin that is
doped with a transition metal, such as cobalt or iron/nickel, is a
metal that is suitable as an anode material in these types of
batteries. Oxides allowing lithium to be doped or undoped in or out
from the oxide at a relatively basic potential, such as iron oxide,
ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide,
and tin oxide, and nitrides, similarly, are usable as the
negative-active materials.
[0088] Suitable positive-active materials for the positive
electrodes include any material known in the art, for example,
lithium nickelate (e.g., Li.sub.1+xNiM'O.sub.2 where x is equal to
or greater than zero and equal to or less than 0.2), lithium
cobaltate (e.g., Li.sub.1+xCoO.sub.2 where x is equal to or greater
than zero and equal to or less than 0.2), olivine-type compounds
(e.g., Li.sub.1+xFePO.sub.4 where x is equal to or greater than
zero and equal to or less than 0.2), manganate spinel (e.g.,
Li.sub.1+x9Mn.sub.2-y9O.sub.4 (x9 and y9 are each independently
equal to or greater than zero and equal to or less than 0.3, e.g.,
0.ltoreq.x9, y9.ltoreq.0.2 or 0.05.ltoreq.x9, y9.ltoreq.0.15) or
Li.sub.1+x1(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1) (x1 and x2 are
each independently equal to or greater than 0.01 and equal to or
less than 0.3; y1 and y2 are each independently equal to or greater
than 0.0 and equal to or less than 0.3; z1 is equal to or greater
than 3.9 and equal to or less than 4.2), and mixtures thereof.
Various examples of suitable positive-active materials can be found
in international application No. PCT/US2005/047383, filed on Dec.
23, 2005, U.S. patent application Ser. No. 11/485,068, file on Jul.
12, 2006, and International Application, filed on Jun. 22, 2007
under Attorney's Docket No. 3853.1001-015, entitled "Lithium-Ion
Secondary Battery", the entire teachings of all of which are
incorporated herein by reference.
[0089] In one specific embodiment, the positive-active materials
for the positive electrodes of the invention include a lithium
cobaltate, such as Li.sub.(1+x8)CoO.sub.z8. More specifically, a
mixture of about 60-90 wt % (e.g. about 80 wt %) of a lithium
cobaltate, such as Li.sub.(1+x8)CoO.sub.z8, and about 40-10 wt %
(e.g., about 20 wt %) of a manganate spinel, such as
Li.sub.(1+x1)Mn.sub.2O.sub.z1, preferably
Li.sub.(1+x1)Mn.sub.2O.sub.4, is employed for the invention. The
value x1 is equal to or greater than zero and equal to or less than
0.3 (e.g., 0.05.ltoreq.x1.ltoreq.0.2 or
0.05.ltoreq.x1.ltoreq.0.15). The value z1 is equal to or greater
than 3.9 and equal to or greater than 4.2. The value x8 is equal to
or greater than zero and equal to or less than 0.2. The value z8 is
equal to or greater than 1.9 and equal to or greater than 2.1.
[0090] In another specific embodiment, the positive-active
materials for the invention include a mixture that includes a
lithium cobaltate, such as Li.sub.(1+x8)CoO.sub.z8, and a manganate
spinel represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1. The values x1
and x2 are each independently equal to or greater than 0.01 and
equal to or less than 0.3. The values y1 and y2 are each
independently equal to or greater than 0.0 and equal to or less
than 0.3. The value z1 is equal to or greater than 3.9 and equal to
or less than 4.2. A' is at least one member of the group consisting
of magnesium, aluminum, cobalt, nickel and chromium. More
specifically, the lithium cobaltate and the manganate spinel are in
a weight ratio of lithium cobaltate:manganate spinel between about
0.95:0.05 and about 0.9:0.1 to about 0.6:0.4.
[0091] In yet another specific embodiment, the positive-active
materials for the invention include a mixture that includes 100% of
a lithium cobaltate, such as Li.sub.(1+x8)CoO.sub.z8.
[0092] In yet another specific embodiment, the positive-active
materials for the invention include at least one lithium oxide
selected from the group consisting of: a) a lithium cobaltate; b) a
lithium nickelate; c) a manganate spinel represented by an
empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1; d) a
manganate spinel represented by an empirical formula of
Li.sub.(1+x1)Mn.sub.2O.sub.z1 or Li.sub.1+x9Mn.sub.2-y9O.sub.4; and
e) an olivine compound represented by an empirical formula of
Li.sub.(1-x10)A''.sub.x10MPO.sub.4. The values of x1, z1, x9 and y9
are as described above. The value, x2, is equal to or greater than
0.01 and equal to or less than 0.3. The values of y1 and y2 are
each independently equal to or greater than 0.0 and equal to or
less than 0.3. A' is at least one member of the group consisting of
magnesium, aluminum, cobalt, nickel and chromium. The value, x10,
is equal to or greater than 0.05 and equal to or less than 0.2, or
the value, x10, is equal to or greater than 0.0 and equal to or
less than 0.1. M is at least one member of the group consisting of
iron, manganese, cobalt and magnesium. A'' is at least one member
of the group consisting of sodium, magnesium, calcium, potassium,
nickel and niobium.
[0093] A lithium nickelate that can be used in the invention
includes at least one modifier of either the Li atom or Ni atom, or
both. As used herein, a "modifier" means a substituent atom that
occupies a site of the Li atom or Ni atom, or both, in a crystal
structure of LiNiO.sub.2. In one embodiment, the lithium nickelate
includes only a modifier of, or substituent for, Li atoms ("Li
modifier"). In another embodiment, the lithium nickelate includes
only a modifier of, or substituent for, Ni atoms ("Ni modifier").
In yet another embodiment, the lithium nickelate includes both the
Li and Ni modifiers. Examples of Li modifiers include barium (Ba),
magnesium (Mg), calcium (Ca) and strontium (Sr). Examples of Ni
modifiers include those modifiers for Li and, in addition, aluminum
(Al), manganese (Mn) and boron (B). Other examples of Ni modifiers
include cobalt (Co) and titanium (Ti). Preferably, the lithium
nickelate is coated with LiCoO.sub.2. The coating can be, for
example, a gradient coating or a spot-wise coating.
[0094] One particular type of a lithium nickelate that can be used
in the invention is represented by an empirical formula of
Li.sub.x3Ni.sub.1-z3M'.sub.z3O.sub.2 where 0.05<x3<1.2 and
0<z3<0.5, and M' is one or more elements selected from a
group consisting of Co, Mn, Al, B, Ti, Mg, Ca and Sr. Preferably,
M' is one or more elements selected from a group consisting of Mn,
Al, B, Ti, Mg, Ca and Sr.
[0095] Another particular type of a lithium nickelate that can be
used in the invention is represented by an empirical formula of
Li.sub.x4A*.sub.x5Ni.sub.(1-y4-z4)Co.sub.y4Q.sub.z4O.sub.a where x4
is equal to or greater than about 0.1 and equal to or less than
about 1.3; x5 is equal to or greater than 0.0 and equal to or less
than about 0.2; y4 is equal to or greater than 0.0 and equal to or
less than about 0.2; z4 is equal to or greater than 0.0 and equal
to or less than about 0.2; a is greater than about 1.5 and less
than about 2.1; A* is at least one member of the group consisting
of barium (Ba), magnesium (Mg) and calcium (Ca); and Q is at least
one member of the group consisting of aluminum (Al), manganese (Mn)
and boron (B). Preferably, y4 is greater than zero. In one
preferred embodiment, x5 is equal to zero, and z4 is greater than
0.0 and equal to or less than about 0.2. In another embodiment, z4
is equal to zero, and x5 is greater than 0.0 and equal to or less
than about 0.2. In yet another embodiment, x5 and z4 are each
independently greater than 0.0 and equal to or less than about 0.2.
In yet another embodiment, x5, y4 and z4 are each independently
greater than 0.0 and equal to or less than about 0.2. Various
examples of lithium nickelates where x5, y4 and z4 are each
independently greater than 0.0 and equal to or less than about 0.2,
can be found in U.S. Pat. Nos. 6,855,461 and 6,921,609 (the entire
teachings of which are incorporated herein by reference).
[0096] A specific example of the lithium nickelate is
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2. A preferred specific
example is LiCoO.sub.2-coated
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2. In a spot-wise coated
cathode, LiCoO.sub.2 doe not fully coat the nickelate core
particle. The composition of
LiNi.sub.0.8Co.sub.0.15Al.sub.0.05O.sub.2 coated with LiCoO.sub.2
can naturally deviate slightly in composition from the
0.8:0.15:0.05 weight ratio between Ni:Co:Al. The deviation can
range about 10-15% for the Ni, 5-10% for Co and 2-4% for Al.
Another specific example of the lithium nickelate is
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. A preferred
specific example is LiCoO.sub.2-coated
Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2. The composition
of Li.sub.0.97Mg.sub.0.03Ni.sub.0.9Co.sub.0.1O.sub.2 coated with
LiCoO.sub.2 can deviate slightly in composition from the
0.03:0.9:0.1 weight ratio between Mg:Ni:Co. The deviation can range
about 2-4% for Mg, 10-15% for Ni and 5-10% for Co. Another
preferred nickelate that can be used in the present invention is
Li(Ni.sub.1/3Co.sub.1/3Mn.sub.1/3)O.sub.2, also called "333-type
nickelate." This 333-type nickelate optionally can be coated with
LiCoO.sub.2, as described above.
[0097] Suitable examples of lithium cobaltates that can be used in
the invention include Li.sub.1+x8CoO.sub.2 that is modified by at
least one of Li or Co atoms. Examples of the Li modifiers are as
described above for Li of lithium nickelates. Examples of the Co
modifiers include the modifiers for Li and aluminum (Al), manganese
(Mn) and boron (B). Other examples include nickel (Ni) and titanium
(Ti) and, in particular, lithium cobaltates represented by an
empirical formula of
Li.sub.x6M'.sub.(1-y6)Co.sub.(1-z6)M''.sub.z6O.sub.2, where x6 is
greater than 0.05 and less than 1.2; y6 is equal to or greater than
0 and less than 0.1, z6 is equal to or greater than 0 and less than
0.5; M' is at least one member of magnesium (Mg) and sodium (Na)
and M'' is at least one member of the group consisting of manganese
(Mn), aluminum (Al), boron (B), titanium (Ti), magnesium (Mg),
calcium (Ca) and strontium (Sr), can be used in the invention.
Another example of a lithium cobaltate that can be used in the
invention is unmodified Li.sub.1+x8CoO.sub.2, such as LiCoO.sub.2.
In one specific embodiment, the lithium cobaltate (e.g.,
LiCoO.sub.2) doped with Mg and/or coated with a refractive oxide or
phosphate, such as ZrO.sub.2 or Al(PO.sub.4).
[0098] It is particularly preferred that lithium oxide compounds
employed have a spherical-like morphology, since it is believed
that this improves packing and other production-related
characteristics.
[0099] Preferably, a crystal structure of each of the lithium
cobaltate and lithium nickelate is independently a R-3m type space
group (rhombohedral, including distorted rhombohedral).
Alternatively, a crystal structure of the lithium nickelate can be
in a monoclinic space group (e.g., P2/m or C2/m). In a R-3m type
space group, the lithium ion occupies the "3a" site (x=0, y=0 and
z=0) and the transition metal ion (i.e., Ni in a lithium nickelate
and Co in a lithium cobaltate) occupies the "3b" site (x=0, y=0,
z=0.5). Oxygen is located in the "6a" site (x=0, y=0, z=z0, where
z0 varies depending upon the nature of the metal ions, including
modifier(s) thereof).
[0100] Examples of olivine compounds that are suitable for use in
the invention are generally represented by a general formula
Li.sub.1-x2A''.sub.x2MPO.sub.4, where x2 is equal to or greater
than 0.05, or x2 is equal to or greater than 0.0 and equal to or
greater than 0.1; M is one or more elements selected from a group
consisting of Fe, Mn, Co, or Mg; and A'' is selected from a group
consisting of Na, Mg, Ca, K, Ni, Nb. Preferably, M is Fe or Mn.
More preferably, LiFePO.sub.4 or LiMnPO.sub.4, or both are used in
the invention. In a preferred embodiment, the olivine compounds are
coated with a material having relatively high electrical
conductivity, such as carbon. In a more preferred embodiment,
carbon-coated LiFePO.sub.4 or carbon-coated LiMnPO.sub.4 is
employed in the invention. Various examples of olivine compounds
where M is Fe or Mn can be found in U.S. Pat. No. 5,910,382 (the
entire teachings of which are incorporated herein by
reference).
[0101] The olivine compounds typically have a small change in
crystal structure upon charging/discharging, which generally makes
the olivine compounds superior in terms of cycle characteristics.
Also, safety is generally high, even when a battery is exposed to a
high temperature environment. Another advantage of olivine
compounds (e.g., LiFePO.sub.4 and LiMnPO.sub.4) is their relatively
low cost.
[0102] Manganate spinel compounds have a manganese base, such as
LiMn.sub.2O.sub.4. While the manganate spinel compounds typically
have relatively low specific capacity (e.g., in a range of about
110 to 115 mAh/g), they have relatively high power delivery when
formulated into electrodes and typically are safe in terms of
chemical reactivity at higher temperatures. Another advantage of
the manganate spinel compounds is their relatively low cost.
[0103] One type of manganate spinel compounds that can be used in
the invention is represented by an empirical formula of
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1, where A' is
one or more of Mg, Al, Co, Ni and Cr; x1 and x2 are each
independently equal to or greater than 0.01 and equal to or less
than 0.3; y1 and y2 are each independently equal to or greater than
0.0 and equal to or less than 0.3; z1 is equal to or greater than
3.9 and equal to or less than 4.1. Preferably, A' includes a
M.sup.3+ ion, such as Al.sup.3+, Co.sup.3+, Ni.sup.3+ and
Cr.sup.3+, more preferably Al.sup.3+. The manganate spinel
compounds of Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1
can have enhanced cyclability and power compared to those of
LiMn.sub.2O.sub.4. Another type of manganate spinel compounds that
can be used in the invention is represented by an empirical formula
of Li.sub.(1+x1)Mn.sub.2O.sub.z1, where x1 and z1 are each
independently the same as described above. Alternatively, the
manganate spinel for the invention includes a compound represented
by an empirical formula of Li.sub.1+x9Mn.sub.2-y9O.sub.z9 where x9
and y9 are each independently equal to or greater than 0.0 and
equal to or less than 0.3 (e.g., 0.05.ltoreq.x9, y9.ltoreq.0.15);
and z9 is equal to or greater than 3.9 and equal to or less than
4.2. Specific examples of the manganate spinel that can be used in
the invention include LiMn.sub.1.9Al.sub.0.1O.sub.4,
Li.sub.1+x1Mn.sub.2O.sub.4, Li.sub.1+x7Mn.sub.2-y7O.sub.4, and
their variations with Al and Mg modifiers. Various other examples
of manganate spinel compounds of the type
Li.sub.(1+x1)(Mn.sub.1-y1A'.sub.y2).sub.2-x2O.sub.z1 can be found
in U.S. Pat. Nos. 4,366,215; 5,196,270; and 5,316,877 (the entire
teachings of which are incorporated herein by reference).
[0104] It is noted that the suitable cathode materials described
herein are characterized by empirical formulas that exist upon
manufacture of lithium-ion batteries in which they are
incorporated. It is understood that their specific compositions
thereafter are subject to variation pursuant to their
electrochemical reactions that occur during use (e.g., charging and
discharging).
[0105] Examples of suitable non-aqueous electrolytes include a
non-aqueous electrolytic solution prepared by dissolving an
electrolyte salt in a non-aqueous solvent, a solid electrolyte
(inorganic electrolyte or polymer electrolyte containing an
electrolyte salt), and a solid or gel-like electrolyte prepared by
mixing or dissolving an electrolyte in a polymer compound or the
like.
[0106] The non-aqueous electrolytic solution is typically prepared
by dissolving a salt in an organic solvent. The organic solvent can
include any suitable type that has been generally used for
batteries of this type. Examples of such organic solvents include
propylene carbonate (PC), ethylene carbonate (EC), diethyl
carbonate (DEC), dimethyl carbonate (DMC), 1,2-dimethoxyethane,
1,2-diethoxyethane, .gamma.-butyrolactone, tetrahydrofuran,
2-methyl tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane,
diethyl ether, sulfolane, methylsulfolane, acetonitrile,
propionitrile, anisole, acetate, butyrate, propionate and the like.
It is preferred to use cyclic carbonates such as propylene
carbonate, or chain carbonates such as dimethyl carbonate and
diethyl carbonate. These organic solvents can be used singly or in
a combination of two types or more.
[0107] Additives or stabilizers may also be present in the
electrolyte, such as VC (vinyl carbonate), VEC (vinyl ethylene
carbonate), EA (ethylene acetate), TPP (triphenylphosphate),
phosphazenes, biphenyl (BP), cyclohexylbenzene (CHB),
2,2-diphenylpropane (DP), lithium bis(oxalato)borate (LiBoB),
ethylene sulfate (ES) and propylene sulfate. These additives are
used as anode and cathode stabilizers, flame retardants or gas
releasing agents, which may make a battery have higher performance
in terms of formation, cycle efficiency, safety and life.
[0108] The solid electrolyte can include an inorganic electrolyte,
a polymer electrolyte and the like insofar as the material has
lithium-ion conductivity. The inorganic electrolyte can include,
for example, lithium nitride, lithium iodide and the like. The
polymer electrolyte is composed of an electrolyte salt and a
polymer compound in which the electrolyte salt is dissolved.
Examples of the polymer compounds used for the polymer electrolyte
include ether-based polymers such as polyethylene oxide and
cross-linked polyethylene oxide, polymethacrylate ester-based
polymers, acrylate-based polymers and the like. These polymers may
be used singly, or in the form of a mixture or a copolymer of two
kinds or more.
[0109] A matrix of the gel electrolyte may be any polymer insofar
as the polymer is gelated by absorbing the above-described
non-aqueous electrolytic solution. Examples of the polymers used
for the gel electrolyte include fluorocarbon polymers such as
polyvinylidene fluoride (PVDF),
polyvinylidene-co-hexafluoropropylene (PVDF-HFP) and the like.
[0110] Examples of the polymers used for the gel electrolyte also
include polyacrylonitrile and a copolymer of polyacrylonitrile.
Examples of monomers (vinyl based monomers) used for
copolymerization include vinyl acetate, methyl methacrylate, butyl
methacylate, methyl acrylate, butyl acrylate, itaconic acid,
hydrogenated methyl acrylate, hydrogenated ethyl acrylate,
acrlyamide, vinyl chloride, vinylidene fluoride, and vinylidene
chloride. Examples of the polymers used for the gel electrolyte
further include acrylonitrile-butadiene copolymer rubber,
acrylonitrile-butadiene- -styrene copolymer resin,
acrylonitrile-chlorinated polyethylene-propylenediene-styrene
copolymer resin, acrylonitrile-vinyl chloride copolymer resin,
acrylonitrile-methacylate resin, and acrlylonitrile-acrylate
copolymer resin.
[0111] Examples of the polymers used for the gel electrolyte
include ether based polymers such as polyethylene oxide, copolymer
of polyethylene oxide, and cross-linked polyethylene oxide.
Examples of monomers used for copolymerization include
polypropylene oxide, methyl methacrylate, butyl methacylate, methyl
acrylate, butyl acrylate.
[0112] In particular, from the viewpoint of oxidation-reduction
stability, a fluorocarbon polymer is preferably used for the matrix
of the gel electrolyte.
[0113] The electrolyte salt used in the electrolyte may be any
electrolyte salt suitable for batteries of this type. Examples of
the electrolyte salts include LiClO.sub.4, LiAsF.sub.6, LiPF.sub.6,
LiBF.sub.4, LiB(C.sub.6H.sub.5).sub.4, LiB(C.sub.2O.sub.4).sub.2,
CH.sub.3SO.sub.3Li, CF.sub.3SO.sub.3Li, LiCl, LiBr and the like.
Generally, a separator separates the positive electrode from the
negative electrode of the batteries. The separator can include any
film-like material having been generally used for forming
separators of non-aqueous electrolyte secondary batteries of this
type, for example, a microporous polymer film made from
polypropylene, polyethylene, or a layered combination of the two.
In addition, if a solid electrolyte or gel electrolyte is used as
the electrolyte of the battery, the separator does not necessarily
need to be provided. A microporous separator made of glass fiber or
cellulose material can in certain cases also be used. Separator
thickness is typically between 9 and 25 .mu.m.
[0114] In some specific embodiments, a positive electrode can be
produced by mixing the cathode powders at a specific ratio. 90 wt %
of this blend is then mixed together with 5 wt % of acetylene black
as a conductive agent, and 5 wt % of PVDF as a binder. The mix is
dispersed in N-methyl-2-pyrrolidone (NMP) as a solvent, in order to
prepare slurry. This slurry is then applied to both surfaces of an
aluminum current collector foil, having a typical thickness of
about 20 um, and dried at about 100-150.degree. C. The dried
electrode is then calendared by a roll press, to obtain a
compressed positive electrode. When LiCoO.sub.2 is solely used as
the positive electrode a mixture using 94 wt % LiCoO.sub.2, 3%
acetylene black, and 3% PVDF is typically used. A negative
electrode can be prepared by mixing 93 Wt % of graphite as a
negative active material, 3 wt % acetylene black, and 4 wt % of
PVDF as a binder. The negative mix was also dispersed in
N-methyl-2-pyrrolidone as a solvent, in order to prepare the
slurry. The negative mix slurry was uniformly applied on both
surfaces of a strip-like copper negative current collector foil,
having a typical thickness of about 10 um. The dried electrode is
then calendared by a roll press to obtain a dense negative
electrode.
[0115] The negative and positive electrodes and a separator formed
of a polyethylene film with micro pores, of thickness 25 um, are
generally laminated and spirally wound to produce a spiral type
electrode element.
[0116] In some embodiments, one or more positive lead strips, made
of, e.g., aluminum, are attached to the positive current electrode,
and then electrically connected to the positive terminal of the
batteries of the invention. A negative lead, made of, e.g., nickel
metal, connects the negative electrode, and then attached to a
feed-through device. An electrolyte of for instance EC:DMC:DEC with
1M LiPF.sub.6, is vacuum filled in the cell casing of a lithium-ion
battery of the invention, where the cell casing has the spirally
wound "jelly roll."
EXEMPLIFICATION
Example 1
Preparation of the CIDs of the Invention
[0117] In this example, a process for manufacturing a CID as shown
in FIG. 1, which includes a first conductive plate, a second
conductive plate, a retainer between the two conductive plates, and
an end plate.
[0118] 1A. Preparation of First Conductive Plate 12
[0119] The first conductive plate (hereinafter "pressure disk") was
formed by stamping a flat sheet of Aluminum 3003 (H0) into a shape
resembling a hat with angled edges, as shown in FIGS. 2A-2C. A flat
aluminum sheet having a thickness of about 0.005 inches (about
0.127 mm) ("d" in FIG. 2C) was used. The flat aluminum sheet was
first depressed using a conical punch with a flat top to thereby
form a conical frustum, a base having a diameter of about 0.315
inches (about 8 mm) ("a" in FIG. 2C), and a flat top at a height of
about 0.03 inches (about 0.762 mm) ("c" in FIG. 2C) from the base.
The diameter of the flat top ("b" in FIG. 2C) was about 0.215
inches (about 5.46 mm). The angle of the frustum relative to a
plane parallel to the base was about 21 degrees. The depressed
aluminum sheet was then trimmed for the base to have a diameter of
about 0.500 inches (about 12.7 mm).
[0120] 1B. Preparation of Second Conductive Plate 24
[0121] The second conductive plate (hereinafter "weld disk") was
manufactured from aluminum in a progressive die. An aluminum stock
(3003 H14) which was about 0.020 inches (about 0.508 mm) thick was
fed into the progressive die where multiple stamping and coining
operations produced a part with an outer diameter of about 0.401
inches (about 10.2 mm), a concentric depression having a diameter
of about 0.100 inches (about 2.54 mm, "a" in FIG. 3C) and a
thickness of about 0.003 inches (about 0.0762 mm) ("c" in FIG. 3C).
Two symmetric trough holes of about 0.040 inches (about 1.02 mm) in
diameter were made to the plate for pressure communication on both
sides of the depression. The holes were located at a distance of
about 0.140 inches (about 3.56 mm) from the center of the
plate.
[0122] 1C. Preparation of Retainer Ring 40
[0123] A retainer ring as shown in FIG. 1, FIG. 8A, and FIG. 8D was
manufactured of polypropylene material by means of injection
molding. The purpose of the retainer ring was to hold the weld disk
at a fixed distance to the pressure disk before, during, and after
the reversal of the pressure disk. The reversal of the pressure
disk occurred when the CID was activated. The retainer ring was
also employed to ensure that the weld disk was electrically
isolated from the pressure risk after its reversal. The retainer
ring included an over-mold feature which secured the weld disk in
place after it had been snapped into the retainer ring.
[0124] 1D. Preparation of the End Plate 34
[0125] An end plate as shown in FIG. 4 can provide a space
necessary for accommodating the pressure disk and for the reversal
of the frustum part of the pressure disk. In this example, the lid
of a battery can was employed as the end plate. The end plate was
manufactured from stamped Aluminum 3003 series (H14).
[0126] For the space necessary for accommodating the pressure disk,
a first cylindrical embossment (or recess 36 in FIG. 4) was created
by milling or alternatively stamping operation onto the lid. The
diameter of the embossment ("a" in FIG. 4) was about 0.505 inches
(about 12.8 mm), which was slightly larger than the outer diameter
of the pressure disk (about 0.500 inches (about 12.7 mm)). The
depth of the first embossment ("b" in FIG. 4) was about 0.0045
inches (about 0.114 mm), which was slightly less then the thickness
of the pressure disk (about 0.005 inches (about 0.127 mm)).
[0127] For the space necessary for accommodating the frustum
portion of the pressure disk upon its reversal, a second concentric
embossment (recess 38 in FIG. 4) was similarly fabricated by
milling or alternatively stamping. This second embossment had a
diameter of about 0.325 inches (about 8.25 mm), which was slightly
larger then the base diameter of the pressure disk frustum (about
0.315 inches (about 8.0 mm)). The second embossment also had a
depth of about 0.029 inches (about 0.737 mm) ("d" in FIG. 4), as
measured from the first embossment, which was slightly larger than
the net height of the pressure disk (about 0.025 inches (about
0.635 mm), "c" in FIG. 3C), as measured from datum line at the base
of the frustum.
[0128] To accommodate a weld pin, a through hole, which was
concentric with the two embossments, was made by drilling or
punching. The hole had a diameter of about 0.100 inches (about 2.54
mm), which was large enough to accommodate the weld pin to be used
for support and cooling of the pressure disk during a spot welding
operation described below.
[0129] 1E. Pre-Cleaning of the Weld Disk, End Plate and Retainer
Ring
[0130] Prior to assembly, the weld disk (24), end plate (34), and
retainer ring (40) were degreased and cleaned with isopropanol
(e.g., 90% isopropanol) in an ultrasonic cleaner. The cleaning was
typically done for about 10 minutes, and dried in low humidity
environment or oven at about 70 degrees Celsius.
[0131] 1F. Assembly
[0132] The components of the CID were assembled as shown in FIG. 1.
The pressure disk (12) was placed in the first embossment (recess
36) of the end plate (34), with the conical frustum facing away
from the end plate. A vacuum suction was used to pull the pressure
disk tightly onto the end plate in order to provide good contact
between the two parts. The two parts were joined hermetically by
means of penetration welding at the middle circumferential region
of base 20 of first conductive plate 12 (e.g., position "a" shown
in FIG. 1).
[0133] The assembled pressure disk/end plate was placed in a spot
weld fixture with a solid Copper (Cu) weld pin that penetrated the
end plate through a hole. The weld pin was used to support and cool
the pressure disk during the spot welding operation later. The weld
disk (24) was placed into the retainer ring. The assembled weld
disk/retainer ring was mounted in the spot weld fixture to hold the
weld disk/retainer ring assembly concentrically in place on top of
the pressure disk. The fixture provided adequate force to push the
weld disk firmly onto the pressure disk, to the point of noticeable
deformation of the pressure disk and weld disk by the weld pin. The
weld disk was attached to the pressure disk with two spot laser
welding in the area deformed and supported by the weld pin. During
the welding operation, the pressure disk was cooled via the weld
pin.
Example 2
Preparation of the Battery of the Invention
[0134] Lithium-ion batteries were prepared using either 100% of
Li.sub.1+xCoO.sub.2(x is about 0-0.2), or a mixture that includes
about 80 wt % of Li.sub.1+xCoO.sub.2 (x is about 0-0.2) and about
20 wt % of Li.sub.1+x9Mn.sub.(2-y9)O.sub.4 (each of x9 and y9 is
independently about 0.05-0.15) as their active cathode materials.
The cell thickness, cell width and cell height of the batteries
were about 18 mm, about 37 mm and about 65-66 mm, respectively.
Anodes of the batteries were of carbon. About 5.5 wt % of biphenyl
(BP) was included in the electrolytes of the batteries. Al tabs and
Ni tabs were employed as the cathode and anode tabs of the
batteries, respectively. The Al tabs of the cathode were welded
onto the second conductive plate of the CID described above in
Example 1. The Ni tabs of the anode of the battery were welded onto
the feed-through device of the battery (see FIG. 8A and FIG.
8D).
Example 3
CID Activation Tests
[0135] The CIDs prepared as described in Example 1, not installed
in battery cells, were tested in this example. For these tests, a
pressure test fixture was designed so that the CID side of the end
plate (34) of the CIDs could be pressurized with compressed air or
nitrogen to test the CID Release Pressure (CRP). The test pressure
was started at about 5 bar (gauge), and increased in 0.5 bar
increments. At each pressure setting, the end plate was kept under
the test pressure for 10 seconds before the pressure increase. The
pressure increase was done gradually between each setting so that
the CRP could be observed with a resolution of a 0.1-0.2 bar. The
test results are summarized in FIG. 10. As shown in FIG. 10, the
average gauge pressure of the CID trip was about 7.7 bar.
Example 4
CID Activation Tests in Lithium-Ion Batteries
[0136] 4A. Lithium-ion Batteries Including a Mixture of
Li.sub.1+xCoO.sub.2 and Li.sub.1+x9Mn.sub.(2-y9)O.sub.4
[0137] For the tests of the example, the lithium-ion batteries that
employed a mixture including about 80 wt % of Li.sub.1+xCoO.sub.2
and about 20 wt % of Li.sub.1+x9Mn.sub.(2-y9)O.sub.4 as their
active cathode materials, as described in Example 2, were
overcharged at 2 C charge rate. Generally, "1 C" represents a
charge rate that would fully recharge the cell, from 1% to 100%
state of charge, in one hour. Thus, with the "2 C" rate, the cell
would be fully recharged in 30 minutes. The CIDs of the tested
batteries were activated between about 5 and 7.5 minutes in average
after the full charge of about 4.2V
[0138] FIG. 11 shows pressure rise rates with respect to the
overcharging voltages. In the tested batteries, the internal
pressure was increased at a rate of about 5 bar per minute at about
4.68 V of overcharge.
[0139] FIG. 12 shows the cell skin temperatures measured when the
CIDs of the tested batteries were activated. As shown in FIG. 12,
the average cell temperature at the time of the CID activation was
about 52.8.degree. C. Generally, after the CID activation, the cell
temperatures were kept increasing for a while by another
10-15.degree. C. and then started to drop. FIG. 13 shows the
results of the peak skin temperatures of the tested batteries. As
shown in FIG. 13, the average peak skin temperature for the tested
batteries was about 65.1.degree. C.
[0140] The cell pressures (bar) were calculated based upon the
measured cell thickness during the overcharge tests. For the tested
cells, the average calculated gauge pressure of the CID trip was
about 7.9 bar. FIG. 14 shows the calculated pressures versus the
measured cell skin temperatures of one of the tested batteries. As
shown in FIG. 14, the CID of the battery was activated after about
5-6 minutes after overcharging, and the cell skin temperature
measured at that time was about 55.degree. C. As discussed above,
the cell temperature of the battery was kept increasing for a while
by another 10-15.degree. C., and then started to drop.
[0141] 4B. Lithium-ion Batteries Including 100% of
Li.sub.1+xCoO.sub.2
[0142] For the tests of the example, the lithium-ion batteries that
employed 100% of Li.sub.1+xCoO.sub.2 as their active cathode
materials, as described in Example 2, were employed. The batteries
were overcharged at 2 C charge rate, as described above in Example
4A. The average cell skin temperature of the batteries when their
CIDs were activated was about 65.degree. C., and the cell
temperatures further increased up to about 72.degree. C. FIG. 15
shows an average cell skin temperature of the tested batteries of
Examples 4A and 4B when their CIDs were activated, where cure A
represents batteries of Example 4A and curve B represents batteries
of Example 4B.
[0143] 4C. Control Tests for Lithium-Ion Batteries With
Commercially Available CIDs
[0144] As a comparison, two 18650 commercially available
cylindrical cells (Sony US18650GR: cells A and B of the same
model), each of which employed standard 100% of Li.sub.1+xCoO.sub.2
cell chemistry and a CID, were tested. These cells were overcharged
at 2 C charge rate, as described above in Example 4A. The CIDs of
the Sony cells were activated at a temperature between about
94-96.degree. C. and at about 110-120.degree. C., as shown in FIG.
15 (curve C for 18650 cell A and curve D for 18650 cell B). The
temperature of the cells after their CID activation continued to
increase and reached about 110-126.degree. C. which were very close
to typical thermal runaway temperatures.
[0145] Additional two 18650 commercially available cylindrical
cells (Sony US18650GR: cells C and D of the same model), each of
which employed standard 100% of Li.sub.1+xCoO.sub.2 cell chemistry
and a CID, were tested. The CIDs of these Sony cells were pressure
tested, as described above in Example 3. The CIDs activated at
about 13.8-14.3 bar (gauge pressure) (cell C at about 14.3 bar,
cell D at about 13.8 bar).
[0146] Based upon the results of Examples 4A-4B and control Example
4C, the maximum cell temperatures reached in the batteries of the
invention were significantly lower than the control 18650 cells
with conventional CIDs. It is noted that the batteries of Examples
4A and 4B had greater than twice the volume of control 18650 cells,
and yet exhibited much lower CID activation temperatures and
pressures. Such lower CID activation temperatures and pressures, in
turn, generally relate to reducing the likelihood of thermal
runaway in the cells. Thus, the CIDs of the invention can enable
batteries or cells, particularly relatively large batteries or
cells (e.g., larger than 18650 cells) to exhibit highly improved
safety-related characteristics.
EQUIVALENTS
[0147] While this invention has been particularly shown and
described with references to example embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *