U.S. patent application number 15/560206 was filed with the patent office on 2018-02-15 for capacitor-battery hybrid formed by plasma powder electrode coating.
The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC, Haijing LIU. Invention is credited to Xiaohong Q. Gayden, Haijing Liu, Zhiqiang Yu.
Application Number | 20180048040 15/560206 |
Document ID | / |
Family ID | 56975911 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180048040 |
Kind Code |
A1 |
Liu; Haijing ; et
al. |
February 15, 2018 |
CAPACITOR-BATTERY HYBRID FORMED BY PLASMA POWDER ELECTRODE
COATING
Abstract
Atmospheric plasma spray devices and methods are used in the
making of the electrodes for both a lithium-ion battery and a
lithium-ion utilizing capacitor structure, which are to be placed
in a common container and infiltrated with a common lithium-ion
transporting, liquid electrolyte. The lithium-ion-utilizing
capacitor and lithium-ion cell battery are combined such that the
respective electrodes may be electrically connected, either in
series or parallel connection for in energy storage and management
in an automotive vehicle or other electrical power supply
application.
Inventors: |
Liu; Haijing; (Shanghai,
CN) ; Gayden; Xiaohong Q.; (West Bloomfield, MI)
; Yu; Zhiqiang; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LIU; Haijing
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Shanghai
DETROIT |
MI |
CN
US |
|
|
Family ID: |
56975911 |
Appl. No.: |
15/560206 |
Filed: |
March 25, 2015 |
PCT Filed: |
March 25, 2015 |
PCT NO: |
PCT/CN2015/075046 |
371 Date: |
September 21, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01G 11/66 20130101;
H01M 2/024 20130101; H01M 10/0459 20130101; H01G 11/62 20130101;
H01M 4/505 20130101; H01G 11/72 20130101; H01M 4/661 20130101; H01M
10/0525 20130101; H01M 10/4264 20130101; Y02E 60/122 20130101; H01M
12/02 20130101; H01G 11/78 20130101; H01M 4/0404 20130101; H01G
11/24 20130101; Y02T 10/7011 20130101; H01G 11/06 20130101; H01G
11/28 20130101; Y02E 60/10 20130101; Y02E 60/13 20130101; H01G
11/86 20130101; Y02T 10/70 20130101; H01M 10/0568 20130101; H01G
11/58 20130101; H01M 12/005 20130101; H01G 11/08 20130101; H01M
10/0583 20130101; H01M 4/485 20130101; H01G 11/34 20130101; Y02T
10/7022 20130101; H01M 2220/20 20130101; H01G 11/46 20130101; H01M
16/00 20130101 |
International
Class: |
H01M 12/00 20060101
H01M012/00; H01M 4/66 20060101 H01M004/66; H01G 11/08 20060101
H01G011/08; H01G 11/06 20060101 H01G011/06; H01G 11/46 20060101
H01G011/46; H01G 11/86 20060101 H01G011/86; H01G 11/58 20060101
H01G011/58; H01G 11/66 20060101 H01G011/66; H01G 11/34 20060101
H01G011/34; H01M 4/04 20060101 H01M004/04; H01G 11/24 20060101
H01G011/24 |
Claims
1. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) a capacitor that both use a common lithium ion
conducting electrolyte; the method comprising: forming porous
positive and negative electrode material layers for the capacitor
by separately using an atmospheric plasma stream to deposit
particles of capacitor positive electrode material as a porous
positive electrode layer bonded to a one side of a porous separator
member or to a metal positive electrode current collector, and,
separately, to deposit particles of capacitor negative electrode
material as a porous negative electrode layer bonded to the
opposing side of a porous separator member or to a metal negative
electrode current collector, at least one of the positive and
negative electrode materials being of a composition to work with
the electrolyte used with the lithium-ion battery; assembling one
or more pairs of capacitor positive and negative electrodes as a
capacitor with each positive electrode layer bonded to a porous
separator on one of its layer sides and to a positive electrode
current collector on the other of its layer sides, and with one
layer side of each negative electrode layer bonded to the opposite
side of a porous separator from a positive electrode layer and to a
negative electrode current collector on the other of its negative
electrode layer sides; placing the assembled capacitor in a
container with a lithium-ion battery comprising one or more pairs
of porous layer, positive and negative electrode members with
corresponding porous separators ; and infiltrating the porous
electrodes and separators of the capacitor and the porous layer
electrodes and separators of the lithium-ion battery with the same
lithium ion conducting liquid electrolyte composition.
2. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) a capacitor as stated in claim 1 in which porous
layer electrodes and separators of the lithium-ion battery are
formed with like sizes and shapes as the electrodes and separators
for the capacitor.
3. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 1 in which particles of
capacitor positive electrode material are deposited as a positive
capacitor electrode layer on one side of a porous separator and
particles of a capacitor negative electrode layer are deposited as
a negative capacitor electrode layer on the other side of the
porous separator layer.
4. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 3 in which particles of metal
current collector material are deposited on the sides of each of
the positive electrode layer and the negative electrode layer that
are not bonded to the porous separator.
5. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 4 in which a layer of positive
electrode material is deposited on the exposed side of the positive
electrode current collector and a layer of negative electrode
material is deposited on the exposed side of the negative electrode
current collector.
6. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 1 in which layers of capacitor
positive electrode material are deposited on both sides of a
positive current collector foil to form a positive capacitor
electrode, layers of capacitor negative electrode material are
deposited on both sides of a negative current collector foil to
form a capacitor negative electrode, and the capacitor electrodes
are placed on opposite sides of a porous separator.
7. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 6 in which the positive
current collector foil is an aluminum foil and the negative current
collector foil is a copper foil.
8. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 1 in which the capacitor
positive electrode material comprises activated carbon or
graphite.
9. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 1 in which the capacitor
negative electrode material comprises activated carbon or
graphite.
10. A method of forming a hybrid combination of a (i) lithium-ion
battery and (ii) as recited in claim 1 in which the capacitor
positive electrode material comprises activated carbon and the
capacitor negative electrode material comprises
Li.sub.4Ti.sub.5O.sub.12.
11. A method of making a combination of (i) a lithium-ion battery
and (ii) a capacitor comprising an electrode that uses the
lithium-containing electrolyte composition of the lithium-ion
battery, for placement of the capacitor and battery in a common
container for use with a common lithium ion conducting electrolyte;
the capacitor comprising a plurality of positive capacitor
electrode layers and of negative capacitor electrode layers, one
side of each positive electrode layer facing one side of a negative
electrode layer with the facing sides of the electrode layers being
physically separated by a porous separator layer, and the opposing
sides of the electrode layers being bonded to current collector
foils; the method comprising: heating particles of positive
capacitor electrode material in an atmospheric plasma stream and
depositing the heated particles as a porous positive capacitor
electrode layer, either on the surface of a metal current collector
foil for the positive electrode material or on one surface of a
porous capacitor separator with two opposing surfaces; heating
particles of negative capacitor electrode material in an
atmospheric plasma stream and depositing the heated particles as a
porous negative capacitor electrode layer, either on the surface of
a metal current collector foil for the negative electrode material
or on the opposing surface of the porous capacitor separator;
completing the formation of the capacitor with a surface of each of
the atmospheric plasma-deposited positive and negative electrode
layers separated from electrical contact by a porous separator and
with the opposite surface of each capacitor electrode being covered
and bonded for electrical contact with a metal current collector
shaped with a connector tab for electrical contact with another
electrode member; placing the capacitor in a common container with
a lithium-ion battery comprising porous battery electrodes and
separators, but with the capacitor and lithium-ion battery
separated from physical contact with each other; and infiltrating
the electrodes and separators of the capacitor and battery with a
common lithium ion-conducting electrolyte.
12. A method of making a combination of (i) a lithium-ion battery
and (ii) a capacitor as recited in claim 11 in which particles of
capacitor positive electrode material are plasma deposited on both
sides of a metal current collector to form a capacitor positive
electrode, particles of capacitor negative electrode material are
plasma deposited on both sides of a metal current collector to form
a capacitor negative electrode, and the positive and negative
electrodes are placed on opposite sides of a porous separator.
13. A method of making a combination of (i) a lithium-ion battery
and (ii) a capacitor as recited in claim 11 in which particles of
capacitor positive electrode material are plasma deposited as a
positive electrode layer on one side of a porous capacitor
separator, particles of capacitor negative electrode material are
plasma deposited as a negative electrode layer on the opposite side
of a porous capacitor separator, and metallic current collectors
with connector tabs are formed on the exposed sides of the positive
electrode layer and the negative electrode layer.
14. A method of making electrode materials for a positive
electrode-separator-negative electrode structure of a capacitor
which is to be used in combination with a positive
electrode-separator-negative electrode structure of a lithium-ion
battery, the capacitor electrode materials being compatible with
like-made electrode materials for the lithium-ion battery, the
capacitor electrode materials and lithium-ion battery electrode
materials being made for use with a common lithium-conducting
electrolyte and placement in a common container as a hybridized
combination, the method comprising: depositing particles, which are
dispersed and heated in an atmospheric plasma stream, as a porous
layer of capacitor positive electrode material, deposited, either
on a surface of a metal current collector foil for the positive
electrode material or on a surface of a porous capacitor separator
with two opposing surfaces, to form a porous layer of positive
electrode material with one layer side contacting the current
collector foil, or the surface of the separator, and with an
opposing positive electrode material layer side; separately
depositing particles, which are dispersed and heated in an
atmospheric plasma stream, as a layer of capacitor negative
electrode material, either on the surface of a metal current
collector foil for the negative electrode material or on one
surface of a porous capacitor separator with two opposing surfaces,
to form a porous layer of negative electrode material with one
layer side contacting the negative current collector foil, or the
surface of the separator, and an opposing negative electrode
material layer side; and using the plasma deposited layer of
capacitor positive electrode material and the plasma deposited
layer of capacitor negative electrode material in an assembly of a
layered capacitor structure comprising a porous separator with a
layer of capacitor positive electrode material on one separator
surface and a layer of capacitor negative electrode material on the
opposing separator surface, and each of the layers of capacitor
electrode material having a current collector foil on their
opposing material layer side.
15. A method of making electrode materials for a capacitor as
recited in claim 14 in which a layer of capacitor positive
electrode particles are plasma deposited on each side of a metallic
current collector foil to form a positive capacitor electrode; a
layer of capacitor negative electrode materials are plasma
deposited on each side of a metallic current collector foil to form
a negative capacitor electrode; and the positive capacitor
electrode is placed with one of its layers of electrode particles
against one side of a porous separator and the negative electrode
is placed with one of its layers of electrode particles against the
opposite side of the porous separator to form the positive
electrode-separator-negative electrode structure of a
capacitor.
16. A method of making electrode materials for a capacitor as
recited in claim 14 in which a layer of capacitor positive
electrode particles are plasma deposited on one side of a porous
separator; a layer of particles of a metallic current collector are
deposited on the layer of particles of capacitor positive electrode
material, and a layer of capacitor positive electrode particles are
plasma deposited on the metallic current collector layer; and a
layer of capacitor negative electrode particles are plasma
deposited on the opposite side of the porous separator; a layer of
particles of a metallic current collector are deposited on the
layer of particles of capacitor negative electrode material, and a
layer of capacitor negative electrode particles are plasma
deposited on the metallic current collector layer to form the to
form the positive electrode-separator-negative electrode structure
of a capacitor.
17. A method of making electrode materials for a capacitor as
recited in claim 15 and further comprising placing the positive
electrode-separator-negative electrode structure of the capacitor
into a common container with, but spaced from, the positive
electrode-separator-negative electrode structure of a lithium
battery and impregnating the electrodes and separators of both the
capacitor and lithium-ion battery with a liquid, lithium-conducting
electrolyte.
18. A method of making electrode materials for a capacitor as
recited in claim 16 and further comprising placing the positive
electrode-separator-negative electrode structure of the capacitor
into a common container with, but spaced from, the positive
electrode-separator-negative electrode structure of a lithium
battery and impregnating the electrodes and separators of both the
capacitor and lithium-ion battery with a liquid, lithium-conducting
electrolyte.
19. A method of making electrode materials for a capacitor as
recited in claim 17 in which a plurality of positive
electrode-separator-negative electrode structures are placed in the
common container with intervening separators and with the positive
electrodes connected to a positive electrode terminal and the
negative electrodes connected to a negative electrode terminal.
20. A method of making electrode materials for a capacitor as
recited in claim 18 in which a plurality of positive
electrode-separator-negative electrode structures are placed in the
common container with intervening separators and with the positive
electrodes connected to a positive electrode terminal and the
negative electrodes connected to a negative electrode terminal.
Description
TECHNICAL FIELD
[0001] A combination of a lithium-utilizing capacitor and a
lithium-ion battery is made in which each member of the combination
comprises porous electrode layers prepared by using atmospheric
plasma coating devices and processes. The layered, electrochemical,
capacitor and battery are assembled in a common pouch and
electrically interconnected as a hybridized capacitor-battery,
suitable for providing balanced energy and power to electrical load
demanding devices.
BACKGROUND OF THE INVENTION
[0002] Electric powered automotive vehicles use multi-cell
batteries to provide electrical energy for providing electrical
power for driving the vehicle and for providing electrical energy
to many devices on the vehicle. Batteries comprising many
lithium-ion electrochemical cells are examples of such electrical
power sources. And such batteries are used in many non-automotive
applications.
[0003] In some applications it may be useful to combine a
lithium-ion battery with an electrochemical capacitor which also
uses lithium ions. For example, such capacitors may be charged
during braking of the vehicle and the stored electrical charge used
later in recharging cells of a lithium-ion battery.
[0004] There is a need for manufacturing practices to jointly
prepare cells for lithium-ion batteries and such electrochemical
capacitors for efficiency in their mutual interconnection and
interaction.
SUMMARY OF THE INVENTION
[0005] It is believed that there are applications in electrically
powered automotive vehicles (and in non-automotive applications) in
which suitable lithium-containing capacitor structures and suitable
lithium-ion battery structures may be placed close to each other,
as in a common pouch or like container, and share a common volume
of a lithium-ion conducting electrolyte, with a suitable amount of
electrolyte constituents for both devices. A hybridized combination
of capacitor and battery is thus provided. The capacitor and
battery each use lithium, and a lithium-ion conducting electrolyte,
in its electrochemical function.
[0006] Here the capacitors include (1) electric double layer
capacitors (ELDC), (2) supercapacitors, and (3) hybridcapacitors.
An ELDC-type capacitor is based on the formation of electric double
layers on the surfaces of electrodes, where cations and anions of
an electrolyte form Helmholz layers on the surfaces of both
electrodes. During cell charge-discharge, positive ions such as
lithium cations in the electrolyte adsorb on one electrode while
the negative ions, anions such as (PF.sub.6).sup.- adsorb on the
other electrode. The fundamental process is adsorption and
desorption, which enables the faster rate of charging and
discharging. Supercapacitors utilize the hybridization of electric
double layer capacitance with redox capacitance, where the
composite electrode material is prepared to consist of porous
carbon and fine metal particles. Hybridcapacitors (or asymmetric
supercapacitors) are proposed to get high capacitance and high
energy density using different material at the two electrodes,
anode and cathode, such as graphitized carbon at the anode and
activated carbon at the cathode, where the
intercalation/de-intercalation of Li.sup.+ at the anode and the
formation of electric double layers at the cathode are intended to
occur.
[0007] In the lithium-ion battery cell, the negative electrode
(anode) releases lithium ions (de-intercalates lithium ions) during
discharging of the cell, and the positive electrode absorbs lithium
ions. The negative electrode releases electrons to the external
circuit and the positive electrode receives them. The reverse
electrochemical process occurs when the battery is charged. The
close proximity of the separate capacitor and lithium-ion battery
cell structures simplifies electrical connections and facilitates
their interaction in providing electrical energy to nearby
electrical loads.
[0008] In such hybrid applications, the outline shapes of the
respective current collectors, porous electrode material layers,
and porous separators may be similar and complementary so as to
suggest the simultaneous manufacture of both the capacitor
electrodes and the battery electrodes and their interrelated
functions. The manufacturing process of this invention is
particularly useful in making hybrid combinations of a
lithium-using capacitor and lithium-ion battery cell.
[0009] In accordance with practices of this invention, atmospheric
plasma spray devices and methods are used to form the porous
particulate electrodes of both a capacitor and a lithium-ion cell.
The plasma-spray methods of forming porous layered electrodes of
the capacitor are comparable and compatible with plasma-spray
methods that may be used for forming the porous layered electrodes
of a lithium-ion battery. In some preferred embodiments of this
invention, the electrodes and separator for a capacitor and the
electrodes and separator for a lithium-ion cell may be prepared
contemporaneously, but separately, and a capacitor and a
lithium-ion cell may be placed, spaced-apart, in a suitable pouch
module or other container and the porous electrodes and separators
infiltrated with a lithium-ion transporting, non-aqueous, liquid
electrolyte.
[0010] In an illustrative example, each member of the capacitor and
battery may be prepared in a rectangular shape of suitable
predetermined dimensions for assembly of the complementary,
hybridized members in operating units. Pre-formed current collector
foils for each of the positive and negative electrodes of the
capacitor and battery may serve as substrates for the plasma
deposition of porous layers of the respective electrode materials.
Such current collector foils are typically flat and are sized with
opposing rectangular surfaces (faces) of suitable area for the
deposit of a suitable layer of selected electrode material on each
side (major face) of the foil. The foil may have an uncoated tab
extending from one side for electrical connection of the electrode
material with other electrodes or with an electrical circuit.
[0011] In another embodiment of the invention, a porous polymer
separator may serve as a substrate for the plasma deposition of
particulate electrode material. A layer of positive capacitor
electrode material may be deposited by plasma deposition on one
side of a suitably sized, rectangular porous separator and a porous
layer of negative capacitor electrode material is deposited by
plasma deposition on the other side of the separator. In each
embodiment, the deposited electrode material and its substrate are
assembled with other members of the capacitor structure. A
complementary lithium battery may be made using a like process.
[0012] Atmospheric plasma spray devices are commercially available,
and practices for their use in the deposition of capacitor
electrode materials and battery electrode materials will be
described and illustrated in more detail below. The deposition
process will be initially described with reference to a capacitor.
But substantially the same practices may be used to make the
members of the battery.
[0013] In summary, a quantity of small particles of electrode
material is prepared. Suitable portions are continually introduced
into a confined stream of unheated air (or other suitable carrier
gas) flowing in a suitable duct or housing. The confined air stream
is directed through a plasma generator, within the housing, in
which the stream-borne particles are momentarily, rapidly heated.
The energized stream of electrode material particles is passed
through a suitable nozzle and directed so as to progressively form
an adherent, porous, particulate coating on a major surface of a
current collector foil or on a major surface of a separator. A
porous layer of the particles is formed having a generally
predetermined uniform thickness. The thickness of the electrode
material layer for the capacitor, which is often in the range of
about 100-200 micrometers, is determined to provide a porous
electrode layer for infiltration with a lithium-ion conducting
electrolyte, to provide suitable lithium ion transporting
properties for the capacitor.
[0014] Examples of suitable anode materials for the capacitor
include graphite, activated carbon, and lithium-titanium containing
oxides and phosphates. Examples of suitable cathode materials
include certain lithium-metal oxides and phosphates, activated
carbon, graphite, and additional materials which will be identified
below in this specification. It may also be helpful to coat some of
the respective electrode material particles with small metal
particles (or other binder materials) which are at least partially
melted or softened in the plasma and serve to bond the electrode
material particles to each other and to their current collector or
separator substrate.
[0015] After the electrode materials for the capacitor have been
suitably deposited on and bonded in a porous layer to their current
collector foils or separators, the assembly of the elements for
formation of a layered capacitor is completed for placement in a
suitable pouch or other module container. Both the capacitor and
the lithium-ion battery may have several layers of electrodes (with
interspersed porous separators) with their respective current
collectors. The current collectors are suitably connected so that
the capacitor and lithium-ion battery each have two terminals. In
preferred embodiments of the invention, an assembly of like-sized
elements of both the capacitor member and the lithium-ion cell
member are placed in the pouch, but the capacitor is separated from
the battery cell. The pores of the electrode members of the
capacitor and the lithium-ion cell, and their respective
separators, are infiltrated with a common lithium ion transporting,
non-aqueous lithium electrolyte solution.
[0016] Other aspects and features of our invention will be further
understood following a more detailed description of illustrated
examples of forming electrodes for capacitors which are to be used
in combination with a lithium-ion cell or group of cells.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic, side view of a positive electrode,
porous separator, and negative electrode of a capacitor placed in a
common pouch with a positive electrode, porous separator, and
negative electrode for a lithium-ion battery cell. In practice,
each of the capacitor and lithium-ion battery would have many
layers of electrode materials deposited on current collectors. The
current collector tabs of the positive electrodes would be suitably
interconnected at a positive terminal and the current collector
tabs of the negative electrodes would be likewise connected at a
negative terminal. The illustrations of the capacitor and lithium
ion battery have been simplified in FIG. 1 by depicting only one of
the seven-layer sets of the electrode and separator elements of
each capacitor unit and lithium-ion battery unit.
[0018] In FIG. 1, a side of the pouch has been removed to show the
layered structures of the capacitor and lithium-ion cell. The
respective electrode materials have been deposited as porous
particulate layers from a plasma spray device onto metal current
collector foils. Each element is a thin rectangular body. The
current collector foils have connector tabs extending from their
upper sides and are arranged for a series-type electric connection
between a hybrid combination of the capacitor and its associated
lithium-ion battery cell. In the series-type connection of FIG. 1
there are four separate current collector leads extending from the
top of the pouch, representing the four terminals of the hybridized
capacitor and lithium-ion battery.
[0019] FIG. 2 is a simplified, schematic side view, with a portion
of the pouch container removed, similar to FIG. 1, of the hybrid
combination of a capacitor and lithium-ion cell. In this hybrid
combination, the capacitor and lithium-ion cell are positioned in a
common pouch in an arrangement in which they are in electrical
parallel-connection for co-delivery of electrical power to an
external circuit. In FIG. 2, only two terminals emerge from the
pouch because the positive electrode tabs of the capacitor and
battery have been connected, as have their negative electrode
tabs.
[0020] FIG. 3A is a schematic illustration of an atmospheric plasma
device, a plasma nozzle supported and adapted to progressively
apply particles of cathode material onto the upper side of an
aluminum current collector foil. The device and coating process may
be used in making electrodes for both capacitors and lithium ion
cells. The aluminum current collector foil is carried on a conveyor
belt or the like. The particles of cathode material may, for
example, be particles of activated carbon for a capacitor cathode
or particles of LiMn.sub.2O.sub.4 for a cathode of a lithium-ion
battery. The particles of electrode material may be coated with
small particles of a metal or of a suitable resin which, when
heated in the plasma device, melt and re-solidify to serve as a
binder to bond the electrode material particles to each other and
to the current collector foil.
[0021] FIG. 3B is an enlarged side view of an aluminum current
collector foil which has been coated on both of its opposing sides
or faces with a bonded layer of positive electrode (cathode)
particles for a lithium-containing capacitor.
[0022] FIG. 3C is an enlarged side view of a copper current
collector foil which has been coated on both of its opposing sides
or faces with a bonded layer of negative electrode (anode)
particles for a lithium-containing capacitor.
[0023] FIG. 4 is an enlarged schematic side view illustration of a
seven layer capacitor structure that is produced using the plasma
spray process illustrated in FIG. 3A. The center layer of the
capacitor structure is a porous polymer separator. Three layers of
materials for the capacitor have been applied, progressively, to
each side of the porous plasma separator. A layer of capacitor
cathode material has been applied to the upper surface of the
separator (as it is shown in FIG. 4), followed by a current
collector foil layer, and a second layer of capacitor cathode
material. Likewise, three layers of material for the anode have
been applied, progressively, to the bottom side of the capacitor as
illustrated in FIG. 4. A lithium-ion battery structure could be
prepared and illustrated in a similar manner.
[0024] 30
DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] In accordance with practices of this invention, hybrid
electrochemical capacitors are prepared, consisting of a capacitor
and a lithium-ion battery which are fabricated by plasma powder
electrode coating technology, delivering a balanced energy-power
performance. Both the capacitor and the battery will adsorb or
intercalate lithium ions and both the capacitor and battery will be
combined in a common pouch or other suitable container.
Accordingly, electrode members for both the capacitor and the
battery may be prepared using atmospheric plasma spray devices or
like plasma deposition devices. As stated, a uniform layer of
particulate electrode material may be deposited over a selected
surface area of a metal foil current collector or over a selected
surface area of a porous separator member. The formation of
electrode layers on current collectors and separator surfaces may
be conducted in sequential or complementary steps to accommodate
the assembly of positive and negative electrodes on opposite sides
of a compatible separator. The positive
electrode-separator-negative electrode structures for a capacitor
and a lithium-ion cell may thus be prepared separately, but
contemporaneously, for assembly into a pouch and infiltration with
a common volume of a non-aqueous, lithium-ion conducting
electrolyte.
[0026] In accordance with practices of this invention, it is
intended that selected electrode materials, for both the
electrochemical capacitor positive and negative electrodes be
prepared in the form of micrometer size particles for deposition on
a selected substrate. The selected electrode material compositions
are deposited on compatible metal current collector foils, or on a
sheet of porous separator material, using one or more atmospheric
plasma spray devices. The particles of electrode materials,
prepared for the plasma deposition, may have been coated with
smaller particles of a metal or of other suitable binder material.
Electrode materials for the lithium-ion cell are likewise
separately prepared and plasma deposited on selected cell
substrates for assembly into lithium-ion cells and placement with a
compatible lithium-ion absorbing capacitor in a container.
[0027] Suitable materials for plasma deposition as cathode
(positive electrode) particles for the capacitor include:
[0028] Metal oxides, MO.sub.x, where M is one or more of Pb, Ge,
Co, Ni, Cu, Fe, Mn, Ru, Rh, Pd, Cr, Mo, W, and Nb.
[0029] A lithium-metal-oxide including: Li.sub.xMO.sub.2 in which M
is Co, Ni, Mn, Cr, or V.
[0030] Li.sub.xM.sub.2O.sub.4 , in which M is Co, Ni, Mn, Cr, or
V.
[0031] Li.sub.xNi.sub.yM.sub.1-yO.sub.2, in which m is Fe or
Mn.
[0032] LiNi.sub.1-x-y-zCo.sub.xM1.sub.yM2.sub.zO.sub.2, in which
M1, M2 are different metals selected from Al, Ni, Co, Fe, Mn, V,
Cr, Ti, W, Ta, or Mo.
[0033] LiMn.sub.2-xM.sub.xO.sub.4 in which M is one of Co, Ni, Fe,
Cu, Cr, V.
[0034] One of LiNiVO.sub.4, LiNbO.sub.3, LiFePO.sub.4,
LiTi.sub.2(PO.sub.4).sub.3, or Li.sub.3V.sub.2(PO.sub.4).sub.3.
[0035] LiMPO.sub.4 in which M is one of Ti, Ge, Zr, Hf.
[0036] One or more of Li.sub.3FeV(PO.sub.4).sub.3,
LiFeNb(PO.sub.4).sub.3, Li.sub.2FeNb(PO.sub.4).sub.3,
Li.sub.xFe.sub.yMn.sub.1-yPO.sub.4, LiMSiO.sub.4 (M=Mn, Fe),
Li.sub.xFe.sub.2(WO.sub.4).sub.3, Li.sub.xFe.sub.2(SO.sub.4).sub.3,
and LiFeO.sub.2.
[0037] A metal sulfide: NiS, Ag.sub.4Hf.sub.3S.sub.8, CuS, FeS, and
FeS.sub.2.
[0038] Activated carbon.
[0039] A polymer such as: poly (3-methyl thiophene), polyaniline,
polypyrrole, poly (para-phenylene), or polyacene.
[0040] As further described in this specification, cathode
particles for the capacitor are usually plasma-deposited on an
aluminum current collector foil or on a porous polymer
separator.
[0041] Suitable materials for plasma deposition as anode (negative
electrode) particles for the capacitor include:
[0042] Li.sub.4Ti.sub.5O.sub.12, LiTi.sub.2O.sub.4, LiCrTiO.sub.4,
LiTi.sub.2(PO.sub.4).sub.3, and graphite or activated carbon.
[0043] Positive electrode material for the capacitor is preferably
plasma deposited on an aluminum current collector foil or on a
polymeric separator such as a porous layer of polyethylene,
polypropylene, or an ethylene-propylene copolymer.
[0044] After the assembling of electrodes and separator and filling
their pores with the electrolyte, the hybrid capacitor and battery
undergo a formation cycle and are then degassed. The plasma powder
coating method can optimize the surface area of the material layers
coated on the foil or the separator, and can also control the
porosity of the respective electrodes, in order to improve both the
energy and power performance of the hybrid capacitor-battery.
[0045] Recently, a lithium and titanium containing spinel
structure, Li.sub.4Ti.sub.5O.sub.12, listed above, has been
demonstrated as a promising negative electrode material for use in
combination with activated carbon as the positive electrode
material for hybrid capacitor applications. Accordingly, the power
density depends on the rate capability of the intercalated compound
Li.sub.4Ti.sub.5O.sub.12, which is associated with the Li-ion
diffusion coefficient and the diffusion distance in the
intercalated compound particle. To obtain a high rate capability,
plasma powder electrode coating technology can be introduced to
develop a nanosize-Li.sub.4Ti.sub.5O.sub.12 electrode with well
controlled porosity, in which conductive metal particle and no
polymer binder will benefit the rate performance. In addition, the
energy density of the capacitor is critically dependent on the
energy density of the carbon positive electrode material. Plasma
powder electrode coating technology can be used to enlarge the
surface area of carbon material in the electrode by size and
porosity optimization to improve the specific capacity.
[0046] The lithium-ion cell component of this capacitor-cell
combination may be formed of like current collector foils and like
porous separator materials.
[0047] Examples of suitable particulate materials for positive
electrodes for lithium-ion cells include lithium manganese nickel
cobalt oxide, lithium manganese oxide, lithium cobalt oxide,
lithium nickel aluminum cobalt oxide, lithium iron phosphate, and
other lithium oxides and phosphates. Examples of particulate
negative electrode materials for lithium-ion cells include lithium
titanate, graphite, activated carbon, and silicon-based materials
such as silicon, silicon-based alloys, SiOx, silicon-tin
composites, and lithium-silicon alloys.
[0048] The common electrolyte for the capacitor cell and the
lithium-ion cell may be a lithium salt dissolved in one or more
organic liquid solvents. Examples of salts include lithium
hexafluorophosphate (LiPF.sub.6), lithium tetrafluoroborate
(LiBF.sub.4), lithium perchlorate (LiClO.sub.4), lithium
hexafluoroarsenate (LiAsF.sub.6), and lithium
trifluoroethanesulfonimide. Some examples of solvents that may be
used to dissolve the electrolyte salt include ethylene carbonate,
dimethyl carbonate, methylethyl carbonate, and propylene carbonate.
There are other lithium salts that may be used and other solvents.
But a combination of lithium salt and non-aqueous liquid solvent is
selected for providing suitable mobility and transport of lithium
ions between the opposing electrodes in the operation of the cell.
The electrolyte is carefully dispersed into and between closely
spaced layers of the electrode elements and separator layers of
each of the capacitor cell and the battery cell. The electrolyte is
not illustrated in the following drawing figures because it is
difficult to illustrate the electrolyte between tightly compacted
electrode layers pressing on an interposed separator.
[0049] A thin porous separator layer is interposed between the
major outer face of the negative electrode material layer and the
major outer face of the positive electrode material layer of each
of the capacitor and the battery unit. The porous separator may be
formed of a porous film or of porous interwoven fibers of suitable
polymer material, or of ceramic particles, or a polymer material
filled with ceramic particles. In the assembly of the hybrid
capacitor and separated lithium-ion cell units, the porous
separator layer is filled with a liquid lithium-ion containing
electrolyte and enables the transport of lithium ions between the
porous electrode members. But the separator layer is used to
prevent direct electrical contact between each of the negative and
positive electrode material layers in each unit, and is shaped and
sized to serve this function.
[0050] FIG. 1 is a schematic illustration of a pouch-contained
assembly 10 of the elements of an electrochemical capacitor 12, a
lithium-ion battery cell 14, and a polymer-coated, metal foil pouch
16 to contain the combined capacitor and cell elements for
electrical series connection to each other and/or to other members
of an electrical circuit. One side of the pouch 16, including the
closure seam of its sides, has been cut-away in the figure to show
the relative positions of the electrochemical capacitor 12 and the
lithium-ion cell 14.
[0051] As stated above in this specification, in actual practice
each capacitor will be formed of several layers of positive
electrodes, negative electrodes, and separators, prepared as
described in the following paragraphs. The like-charged electrode
layers are connected by tabs on their current collectors,
respectively, in a positive terminal and a negative terminal for
the capacitor. The positive and negative tabs for the groups of
positive and negative capacitor electrodes may be connected with
other devices in an electrical circuit as desired. Lithium-ion
batteries are also typically formed of many positive electrodes
connected to a positive terminal and many negative electrodes
connected to a negative terminal. But since the focus of this
specification is on the use of plasma deposition methods and
devices to make such electrodes and separators, the illustrations
of FIGS. 1 and 2 have been simplified to depict the single set of
electrodes for capacitor 12 and lithium-ion cell 14.
[0052] The illustrated electrochemical, capacitor 12 comprises a
positive electrode, which in this example comprises a rectangular
aluminum foil current collector 18 with a connector tab 18'
extending from its top side and through the overlapping surface of
pouch 16. The positive electrode of the capacitor further comprises
porous particulate layers of electrode material 20 which have been
deposited by atmospheric plasma deposition on each face of the
aluminum foil current collector 18. The positive electrode material
for the capacitor may, for example, be activated carbon. The
thickness of the current collector foil 18 may be, for example,
about ten micrometers and the lengths of the sides of the foil may,
for example be in the range of 75 mm to 100 mm, not including the
tab 18'. The porous layers of electrode material 20 may, for
example, be about 10 to 500 micrometers in thickness and applied to
substantially cover the rectangular faces of current collector foil
18, but not tab 18'.
[0053] The electrochemical capacitor 12 further comprises a
negative electrode, which in this example comprises a rectangular
copper foil current collector 22 with a connector tab 22' extending
from its top side and through the overlying surface of pouch 16.
The negative electrode of the capacitor further comprises porous
particulate layers of electrode material 24 which have also been
deposited by atmospheric plasma deposition on each face of the
copper foil current collector 22, but not on tab 22'. The negative
electrode material for the capacitor may, for example, also be
activated carbon. The side lengths and thickness of the copper
current collector foil 22 are suitably like the dimensions of the
positive electrode current collector foil. The porous layers of
negative electrode material 24 may, for example, be of
complementary thickness to that of the positive electrode materials
and applied to substantially cover the rectangular faces of current
collector foil 22, but not tab 22'.
[0054] As illustrated in FIG. 1, the outer surface of one side of
the positive electrode material 20 is placed close against one face
of a porous separator layer 26 and the outer surface of one side of
the negative electrode material is pressed against the opposite
face of the porous separator 26. Porous separator 26 may be formed,
for example, of polyethylene fibers. Separator 26 has a
two-dimensional shape and a thickness. In this example, the
rectangular shape of separator is determined to cover the
contacting surfaces of the respective electrode materials 20, 24
and to physically separate them. The shape and thickness of the
porous separator 26 also serves to retain liquid electrolyte for
lithium absorption and desorption by the electrode layers 20, 24 of
the capacitor. In the assembled device, the pores of the electrode
materials 20, 24 are infiltrated with liquid lithium-ion conducting
electrolyte, as well as the pores of separator 26.
[0055] The liquid electrolyte is not illustrated in FIG. 1, but it
is present in the porous electrode layers and the separators of
each of the assembled capacitor 12 and battery 14. In the capacitor
12, lithium ions are transported between the electrode materials 20
and 24 through the electrolyte.
[0056] The structure of the lithium-ion cell or battery 14 is
similar to that of capacitor 12 and the outline sizes and thickness
of the respective current collector foils, electrode material
layers and separator of battery 14 are comparable to the similar
structural elements of capacitor 12. But the electrode materials
may be different and the electrochemical reactions are
different.
[0057] In this example and simplified illustration, batteryl4
includes an aluminum positive electrode current collector foil 30
with a connector tab 30' extending through the overlying pouch
material 16. Plasma deposited positive electrode layers 32 (e.g.,
activated carbon) are formed on both major faces of the aluminum
current collector foil 30. The positive electrode material 32 for
the battery 14 may, for example, be particles of LiFePO.sub.4. A
copper negative current collector foil 34 with tab 34' is plasma
coated on both of its major faces with layers of negative electrode
material 36. The particle layers of negative electrode material 36
may comprise activated carbon or resin-bonded activated carbon. The
facing porous layers of positive electrode material 32 and of
negative electrode material 36 are kept apart by porous polymer
separator 38. In the assembled battery 14, placed in pouch 16, the
pores of separator 38 and of electrode layers 32 and 36 are filled
with a suitable non-aqueous, lithium-ion conducting electrolyte.
The electrolyte may, for example, comprise lithium
hexafluorophosphate (LiPF.sub.6) dissolved in a mixture of dimethyl
carbonate and methylethyl carbonate as solvent.
[0058] In FIG. 1, the current collector tab leads 18' and 22' for
capacitor 12 and the current collector tab leads 30', 34' for
battery 14, each extend through the adjoining pouch material and
are positioned for serial electrical connections. In a typical
hybrid capacitor, these current collector leads would be the four
terminal posts for the series-connected assembly in pouchl6. Such
an arrangement offers many possibilities for interconnection of the
capacitor electrodes and battery electrodes with each other and
with other members of an electrical power-requiring system. The
electrical connections between capacitor 12 and lithium-ion battery
14 may, for example, be through a DC-DC converter. This type of
electrical interconnection could enable the capacitor 12 to store
energy, for example, when an automotive vehicle is braking, and to
later release energy to the adjacent lithium-ion battery 14 during
vehicle starting or acceleration.
[0059] FIG. 2 illustrates a pouch-contained assembly 110 of a
capacitor 112 and battery 114 which are arranged and oriented in
pouch 116 for parallel electrical connection between capacitor 112
and battery 114. Again, in this simplified illustration only single
electrode structures are illustrated for each of capacitor 112 and
battery 114. In practice, a capacitor and battery would each
comprise many connected positive electrodes with current collector
tabs connected in a single positive terminal and many negative
electrodes with current collector tabs electrically connected in a
single negative terminal.
[0060] In this example and illustration, the electrodes and
separator of capacitor 112 may be substantially identical in shapes
and compositions with respect to the corresponding elements of
capacitor 12 as shown in FIG. 1. And the electrodes and separator
of battery 114 may be substantially identical in shapes and
compositions with respect to the corresponding elements of battery
14 shown in FIG. 1. Accordingly, the corresponding current
collector foils, electrode layers and separators of FIG. 2 are
identified by numerals 1xx (or 1xx') with respect to the same parts
of FIG. 1 which are identified as xx or xx'.
[0061] The main difference between FIG. 1 and FIG. 2 is that
capacitor 112 and battery 114 are arranged and oriented in pouch
116 for parallel electrical connection between capacitor 112 and
battery 114, and for series connection with these combined elements
and electrical power-requiring devices outside pouch 116.
Accordingly, positive electrode tab 118' of capacitor 112 and
positive electrode tab 130' of battery 114 are connected as a
single positive (+) terminal 140 which extends through the top of
pouch 116. In a similar arrangement, negative electrode tab 122' of
capacitor 112 and negative electrode tab 134' of battery 114 are
connected as a single negative (-) terminal 142 which extends
through the top of pouch 116.
[0062] Thus, in the parallel connection arrangement of the
electrodes of capacitor 112 and battery 114, the two components may
be designed to operate in a common voltage window and to achieve a
higher power in their common voltage range.
[0063] FIG. 3A is presented to illustrate the plasma deposition of
heated particles of active positive electrode (cathode during
capacitor discharge) material for a capacitor onto one major face
of an aluminum current collector foil. For example, the capacitor
elements may be shaped and composed like those of capacitor 12 in
FIG. 1, or capacitor 112 in FIG. 2, with its aluminum current
collector foil 18 and positive electrode material 20.
[0064] FIG. 3A illustrates the practice of using an atmospheric
plasma application device 200 to deposit active positive electrode
material particles for a capacitor in a porous layer on a surface
of a metal current collector foil. In this embodiment, the finished
capacitor is intended to be like capacitor 12 as illustrated in
FIG. 1. FIG. 3A is intended to illustrate the method of applying
particles of positive electrode material as electrode material
layer 20 on one side of current collector foil 18. Thus, the
substrate is the upper surface 17 of a copper current collector
foil 18 with its connection tab 18'. Connection tab 18' is not
coated with the electrode material. The active positive electrode
material is particles of commercially available activated carbon
with their extraordinary porosity and surface area. The activated
carbon particles may be coated with a suitable amount of a polymer
binder for bonding of the particles to each other and to surface 17
of the current collector 18.
[0065] In this example, the current collector foil 18 is placed and
carried on a movable work surface 202, such as a conveyor belt, or
the like, for locating the current collector foil 18, with its
upper surface 17, under the plasma application device. This process
may be conducted in air and in a normal ambient workplace
atmosphere.
[0066] In this example, the copper current collector foil 18 is
illustrated in the form of a thin, square layer of about 100
millimeters length on each side, but the capacitor elements are
also often made in other rectangular shapes and dimensions
depending on the intended size of the capacitor elements and
assembled capacitor modules. The copper current collector foil
layer 18 is often about ten to twelve micrometers in thickness. The
substrate 202 is moved and placed in a flat position at ambient
conditions under a suitable atmospheric plasma spray generator
apparatus 200 with a nozzle for directing its flow stream of
electrode material particles. The spray device(s) and/or workpiece
may be carried on a suitable support and moved under suitable
programmable controls for sequential deposition of particulate
electrode material on the surface 17 of one or more copper current
collectors 18.
[0067] In practices of this invention, and with reference to FIG.
3, an atmospheric plasma apparatus 200 may comprise an upstream
round flow chamber 204 (shown partly broken-off in FIG. 3) for the
introduction and conduct of a flowing stream of suitable working
gas, such as air, nitrogen, or an inert gas such as helium or
argon. The flow of the working gas would be introduced above the
broken-off illustration of flow chamber 204 and proceed in a
downward direction. In this embodiment, this illustrative initial
flow chamber 204 is tapered inwardly to smaller round flow chamber
206. Active positive electrode material particles 208 for the
capacitor (for example, activated carbon particles) are delivered
through opposing supply tubes 210, 212 into round flow chamber 206.
Supply tube 208 is shown partially broken-away to illustrate
delivery of the positive capacitor electrode material particles
208. The electrode material particles 208 are suitably introduced
from opposing sides of the apparatus 200 into the working gas
stream in chamber 206 and then carried into a plasma nozzle 214 in
which the air (or other working gas) is converted to a plasma
stream at atmospheric pressure. As the electrode material particles
208 enter the gas stream in chamber 206 they are dispersed and
mixed in the stream and carried by it. As the stream flows through
the downstream plasma-generator nozzle 214, the electrode material
particles 208 are heated by the formed plasma of predetermined and
controlled energy to a precursor processing temperature. The
momentary thermal impact on the electrode material particles may be
a temperature of from about 300.degree. C. up to about 3500.degree.
C. The plasma activated electrode material particles exit nozzle
214 as stream 216.
[0068] In this example, the stream 216 of air-based plasma and
suspended, plasma-activated, activated carbon electrode material
particles is progressively directed by the nozzle 214 to deposit
particles as a layer of electrode material 20 onto the surface of
the upper surface 17 of the copper foil current collector 18. The
nozzle 214 and stream 216 of suspended electrode material is moved
in a suitable path and at a suitable rate such that the particulate
activated carbon electrode material 208 is deposited as a porous
layer 20 of specified thickness of the electrode particles on the
surface 17 of the current collector foil 18.
[0069] The relative movement of the plasma spray stream 216 and/or
the substrate 202 is continues until the entire face 17 of current
collector foil 18 (but not tab 18') is covered with a generally
uniformly thick layer of capacitor positive electrode material 20.
The current collector foil may then be turned over so that its
opposing face is likewise coated with a layer of positive electrode
material 20.
[0070] FIG. 3B is a schematic illustration of a representative
positive electrode for a capacitor, like capacitor 12 in FIG. 1 or
capacitor 112 in FIG. 2. Both major sides of aluminum current
collector foil 18 have been coated, using an atmospheric plasma
spray device, with substantially identical adherent layers of
positive capacitor electrode material 20. Current collector tab 18'
remains exposed for desired inter-connection with other capacitor
electrodes or with battery electrodes or with other electrical
devices.
[0071] The above described plasma spray deposition device and
method may be used to deposit porous layers of particulate negative
capacitor electrode material on a suitable metal foil current
collector material. For example, FIG. 3C illustrates a negative
capacitor electrode that, in this example, consists of a copper
current collector foil 22 (with extended tab 22') coated on both
major faces with generally uniformly thick layers of plasma
deposited negative electrode material 24. For example, the negative
electrode material for the capacitor may also be suitably sized
particles of a commercially-available activated carbon.
[0072] In the above described process, both the positive electrode
and the negative electrode for a capacitor cell were prepared by
plasma deposition of particles of the electrode material onto both
sides of a suitable metal current collector. The assembly of the
capacitor elements is then advanced by placing one face of positive
electrode material against one side of a porous separator and one
face of a negative electrode material against the opposite face of
the separator. The assembled capacitor is illustrated in FIG. 4. In
FIG. 4, the capacitor is identified by numeral 12 because it is
intended to illustrate in perspective view, the capacitor
structures illustrated in side view in FIGS. 1 and 2. As seen in
FIG. 4, and described in downward order from top surface, the seven
layers of capacitor 12 comprise porous layer 20 of positive
capacitor electrode material, copper positive electrode current
collector foil 18 with its uncoated connector tab 18', the opposing
layer of porous positive electrode material 20, porous separator
26, a layer of porous negative capacitor electrode material 24,
aluminum negative electrode current collector foil 22 with its
uncoated connector tab 22', and an opposing layer of porous
positive electrode material 24. It is seen that a layer of positive
electrode material 20 and a layer negative electrode material 24
are pressed against the corresponding faces of the porous separator
26.
[0073] When capacitor 12 has been assembled with a like-shaped and
like- made battery (e.g., battery 14) in a suitable container, like
pouch 16, both the capacitor and battery will be suitably
infiltrated with a shared lithium-ion transporting electrolyte.
[0074] In the above described plasma application process,
particulate cathode material was plasma coated on both sides of an
aluminum current collector foil to form a capacitor cathode, and
particulate anode material was plasma coated onto both sides of a
copper current collector foil to form a capacitor anode. The
assembly of the capacitor cell was then completed by placing a
cathode on one side of a suitable porous separator and a cathode on
the other side of the separator. A like plasma deposition process,
using suitable electrode materials, may be used to make and
assemble a lithium-ion battery cell for the hybrid combination.
[0075] In a second plasma deposition process, similar to that
illustrated in FIG. 3a, particles of cathode electrode material are
deposited on one side of a suitable separator. Then particles of a
current collector metal (e.g., Al) are plasma deposited onto the
particulate cathode layer. Then, a second layer of particulate
cathode material may be plasma deposited on the current collector
layer. Particles of anode electrode material, metal current
collector material, and anode electrode material are then
sequentially plasma deposited onto the opposite side of the
separator. The result of the six layers of plasma-deposited is
equivalent to the seven layer capacitor structure illustrated in
FIG. 4.
[0076] As stated, either plasma deposition process, using
appropriate particulate electrode materials and current collector
material may be used to make the electrochemical cell structures of
either a lithium-ion using capacitor or a lithium-ion battery. The
plasma deposition process can be conducted, for example, in
parallel or other complementary manufacturing lines to
simultaneously produce complementary capacitors and batteries for
assembly into suitable containers for hybrid combination. The
porous elements of the combined assembly are then infiltrated or
impregnated with a suitable lithium ion containing electrolyte. And
capacitor and battery members of the combination may be charged or
otherwise prepared for their respective electrochemical
functions.
[0077] As stated, the layers of the respective electrode material
particles is pre-deposited on a compatible current collector
surface or a compatible separator surface using one or more
atmospheric plasma nozzles or deposition devices. Such plasma
nozzles for this application are commercially available and may
also be carried and used on robot arms, under multi-directional
computer control, to apply suitable electrode particles to coat the
surfaces of each metal current collector foil or separator surface
for a lithium-using capacitor and, separately, for a lithium-ion
cell. Multiple nozzles may be required and arranged in such a way
that a desired coating speed may be achieved in terms coated area
per unit of time.
[0078] The atmospheric plasma nozzle typically has a metallic
tubular housing which provides a flow path of suitable length for
receiving the flow of working gas, receiving and dispersing
particles of electrode material, and for enabling the formation of
the plasma stream in an electromagnetic field established within
the flow path of the tubular housing. The tubular housing
terminates in a conically tapered outlet, shaped to direct a
suitably shaped plasma stream toward an intended substrate to be
coated. An electrically insulating ceramic tube is typically
inserted at the inlet of the tubular housing such that it extends
along a portion of the flow passage. A stream of a working gas,
such as air (or nitrogen or argon), and carrying dispersed
particles of a specified electrode material, is introduced into the
inlet of the nozzle. The flow of the air-particle mixture may be
caused to swirl turbulently in its flow path by use of a swirl
piece with flow openings, also inserted near the inlet end of the
nozzle. A linear (pin-like) electrode is placed at the ceramic tube
site, along the flow axis of the nozzle at the upstream end of the
flow tube. During plasma generation the electrode is powered by a
suitable generator at a frequency in the 0.1 hertz to gigahertz
range and to a suitable potential of a few kilovolts. Plasma
generation technology such as corona discharge, radio wave, and
microwave sources, and the like, may be employed. The metallic
housing of the plasma nozzle is grounded. Thus, an electrical
discharge can be generated between the axial pin electrode and the
housing. No vacuum chamber is used.
[0079] When the generator voltage is applied, the frequency of the
applied voltage and the dielectric properties of the ceramic tube
produce a corona discharge at the stream inlet and the electrode.
As a result of the corona discharge, an arc discharge from the
electrode tip to the housing is formed. This arc discharge is
carried by the turbulent flow of the air/particulate electrode
material stream to the outlet of the nozzle. A reactive plasma of
the air (or other carrier gas) and dispersed electrode particles is
formed at a relatively low temperature. A copper nozzle at the
outlet of the plasma container is shaped to direct the plasma
stream in a suitably confined path against the surfaces of the
current collector substrates for the lithium-ion cell electrode
members. The energy of the plasma may be determined and managed for
the material to be applied.
[0080] Thus, specific examples have been presented for the use of
plasma spray deposition devices and methods in the preparation of
lithium-ion incorporating capacitors and batteries for assembly
into a common container to serve as hybrid electrochemical devices
for provision of electrical power in many devices consuming
electrical energy. The examples are intended to illustrate
practices of the invention and not the scope of the following
claims.
* * * * *