(19) United States
`(12) Patent Application Publication (10) Pub. N0.: US 2003/0013007 A1
`
`Kaun
`(43) Pub. Date:
`Jan. 16, 2003
`
`US 20030013007A1
`
`(54) CELL STRUCTURE FOR
`ELECTROCHEMICAL DEVICES AND
`METHOD OF MAKING SAME
`
`(52) US. Cl.
`
`.............................. 429/94; 429/130; 429/61;
`429/7
`
`(76)
`
`Inventor: Thomas D. Kaun; New Lenox; IL (US)
`
`Correspondence Address:
`FOLEY & LARDNER
`150 EAST GILMAN STREET
`PO. BOX 1497
`
`MADISON, WI 53701-1497 (US)
`
`(21) Appl. No.:
`
`10/192,818
`
`(22)
`
`Filed:
`
`Jul. 10, 2002
`
`Related US. Application Data
`
`(60) Provisional application No. 60/305,339; filed on Jul.
`13; 2001.
`
`Publication Classification
`
`(51)
`
`Int. Cl.7 ............................ H01M 2/18; H01M 6/10;
`H01M 6/50; H01M 10/42
`
`(57)
`
`ABSTRACT
`
`An electrochemical device comprising alternating layers of
`positive and negative electrodes separated from each other
`by separator layers. The electrode layers extend beyond the
`periphery of the separator layers providing superior contact
`between the electrodes and battery terminals; eliminating the
`need for welding the electrode to the terminal. Electrical
`resistance within the battery is decreased and thermal con-
`ductivity of the cell is increased allowing for superior heat
`removal from the battery and increased efficiency. Increased
`internal pressure within the battery can be alleviated without
`damaging or removing the battery from service while keep-
`ing the contents of the battery sealed off from the atmo-
`sphere by a pressure release system. Nonoperative cells
`within a battery assembly can also be removed from service
`by shorting the nonoperative cell thus decreasing battery
`life.
`
`
`
`VARTA Ex. 2013 Page 1 of 23
`PEAG/Audio Partnership v. VARTA
`|PR2020-01212
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`IPR2020-01212
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`Patent Application Publication
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`Jan. 16, 2003 Sheet 1 0f 9
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`US 2003/0013007 A1
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`Patent Application Publication
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`Jan. 16, 2003 Sheet 2 0f 9
`
`US 2003/0013007 A1
`
`
`
`
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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 3 0f 9
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`US 2003/0013007 A1
`
`30
`
`28
`
`FIG.
`
`8
`
`his“as...v,
`
`.13.4w?$9.?
`
`1111.11...
`
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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 4 0f 9
`
`US 2003/0013007 A1
`
`
`
` 5’3
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`

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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 5 0f 9
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`US 2003/0013007 A1
`
`
`
`45
`
`Section
`
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`

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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 6 0f 9
`
`US 2003/0013007 A1
`
`FIG. 11
`
`
`
`
`
`
`
`
`
`
`
`FIG. 12
`
`Current(A), Temperature (°C)_1 vs. Test_Tlme(s)
`
`
`
`-— 1-001 Currenl(A)
`-—14301 Temperature ('C)_1
`
`
`240
`
`190 ~
`
`140
`
`I
`
`1
`
`(D O
`
`.h C
`
`Current(A)
`
`—100 .3:
`
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`
`25.5
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`25
`
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`
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`
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`
`Temperature(°C)_1
`
`Test_Time(s)
`
`VARTA EX. 2013 Page 7 of 23
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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 7 0f 9
`
`US 2003/0013007 A1
`
`FIG. 13
`
`
`
` SpecificEnergy,Whlkg
`
`
`
`
`
`" " Rolled-Ribbon Cell
`“MUHP Round Cell
`
`O
`
`100
`
`200
`
`300
`
`400
`
`500
`
`600
`
`Specific Power (sustained), W/kg
`
`FIG. 14
`
`
`
`30000. 000
`5000 .000
`35000.000
`2500! .000
`40000. 000
`45000000
`
`
`
`
`
`
`
`
`N
`
`
`
`o Current(A)
`
`a Temperature (°C)_1
`
`
`
`
`
`
`
`
`
`
`Time, sec
`
`VARTA EX. 2013 Page 8 0f 23
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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 8 0f 9
`
`US 2003/0013007 A1
`
`FIG. 15
`
`Current(A), Voltag e(V) vs. Test_Time(s)
`
` I
`
`
`
`“‘— 1-001 Current(A)
`
`'
`
`u
`I
`
`\
`
`3.5
`
`VoltageW)
`
`i3
`
`Current(A)
`
`200 *
`
`100 1
`
`0
`
`2140t3.000
`
`21450.000
`
`21500.0
`
`21550.000
`
`2160P.000
`
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`
`2
`
`Test_Time(s)
`
`FIG. 16
`
`
`
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`
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`
`
`
`
`
`
`
`State of Charge (“7.)
`
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`Patent Application Publication
`
`Jan. 16, 2003 Sheet 9 0f 9
`
`US 2003/0013007 A1
`
`FIG. 17
`
`Current(A), Voltage(V) vs. Test_Time(s)
`
`200
`
`
`
`4 5
`
`m
`
`_
`
`a;
`
`‘
`
`
`” 4
`
`" 3.5
`
`-- a
`
`W
`
`2.5
`
`S
`3—
`m
`E
`E
`
`4450.000
`
`450 .000
`
`D“?
`4550.000
`
`—_‘
`4609.020
`
`150 «"""""""""""""""""""""
`
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`
`100
`
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`
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`:4
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`""" 1-001 Voltagg(¥)_
`
`
`
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`
`
`
`0
`
`Test_Time(s)
`
`VARTA EX. 2013 Page 10 0f 23
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`US 2003/0013007 A1
`
`Jan. 16, 2003
`
`CELL STRUCTURE FOR ELECTROCHEMICAL
`DEVICES AND METHOD OF MAKING SAME
`
`[0001] This application claims priority to US. Provisional
`Patent Application No. 60/305,339, filed Jul. 13, 2001, the
`entire contents of which are hereby incorporated by refer-
`ence.
`
`FIELD OF THE INVENTION
`
`[0002] The present invention relates to improved electro-
`chemical devices, such as batteries, capacitors, fuel cells,
`sensors or the like. More specifically this invention relates to
`improved electrochemical devices that provide high specific
`power and energy outputs per weight and volume of the
`device, and to the methods of making these improved
`electrochemical devices.
`
`BACKGROUND OF THE INVENTION
`
`[0003] With the increasing pace of advances in electronics
`there has been a corresponding increase in the need for
`electrochemical devices that provide the energy density,
`efficiency and safety to power advanced electronic devices,
`especially portable electronic devices, while still being eco-
`nomically viable. Older battery configurations are often
`unsuitable to meet these increased demands. Out of envi-
`
`ronmental and efficiency concerns, the reach of electricity
`providing devices has been expanded to new areas including
`hybrid electric vehicles. Ideally, an electrochemical device
`will provide high current density, decrease the internal
`resistance of the battery and effectively manage the thermal
`output of the electrochemical device to increase the longev-
`ity of the device.
`
`[0004] These features can be achieved by providing mas-
`sive and/or large surface-area connections between elec-
`trodes and cell current collectors, and specifically between
`cells in a battery. Generally to preserve high specific energy
`and power, W/kg, Watt-hours per kilogram (Wh/kg) and,
`Watts per kilogram (W/kg), present
`technologies and
`devices fall far short of these goals. A second critical feature
`of the high power device is internal heat removal. High
`power to external circuitry generally generates a like amount
`of energy as heat in short time duration internal to the cell.
`Excessive temperature rise will destroy (e.g. melt
`the
`microporous polymer separator or autoignite the flammable
`organic electrolyte) or significantly shorten the useful life of
`the Li-ion cell.
`
`[0005] An electrochemical device comprised of cathode
`and anode electrodes physically exposed to an electrolyte
`can generically be used to convert between chemical and
`electrical energies. A housing can enclose these electrode
`and electrolyte components, and can even seal them from the
`atmosphere. Batteries, fuel cells and capacitors are but a few
`such specific electrochemical devices to which this inven-
`tion relates.
`
`[0006] As the electrical power in terms of voltage and/or
`amperage of each pair of cathode and anode electrodes (or
`cell) is generally small, many separate pairs of cathode and
`anode electrodes or cells can be used in a single housing.
`Current collectors are generally used to electrically inter-
`connect the cells,
`in parallel and/or in series,
`to provide
`usable voltage and amperage outputs at exposed terminals
`on the electrochemical device.
`
`[0007] The electrochemical device performs usable work
`when ions pass between the electrodes of each cell via the
`electrolyte, and when electrons concurrently pass through
`each cell via the electrodes. The generated voltage per cell
`is predetermined by the electrochemical reaction of the
`component materials used, and the generated amperage
`and/or power available is dependent on the configurations
`and masses of these active components.
`
`[0008] The specific output energy of the device can be
`provided in terms of watts-hours per device weight, and the
`specific output power of the device can be provided in terms
`of watts per device weight. Output values of existing elec-
`trochemical devices are typically small fractions of theo-
`retically possible output values, because of internal resis-
`tances and other inefficiencies (hardware mass and volume).
`
`[0009] The resistance to ion conduction between the elec-
`trode elements is one major source for internal power loss.
`Such resistance, R, can be theoretically determined with the
`expression
`R=p1/A
`
`[0010] where:
`
`“p” (rho) is the impedance value of the elec-
`[0011]
`trolyte;
`
`[0012]
`
`“1” is the thickness of the electrolyte; and
`
`“A” is the interfacial contact area between the
`[0013]
`electrode elements and electrolyte.
`
`[0014] The ionic-impedance value, p, is not easily subject
`to modification and is not effective as a design parameter.
`Designers of electrochemical devices thus strive to reduce
`the electrolyte thickness “1”, and to increase the interfacial
`contact area “A” between the electrode elements and the
`
`electrolyte.
`
`[0015] Different configurations of the cathode and anode
`electrodes, electrolyte separation, and the current collection
`have been proposed. For example, a cathode electrode band
`can be zig-zagged to define separate compartments for
`holding electrolyte, and inserted with elongated rod-like
`anode electrodes into the electrolyte spaced from the cath-
`ode electrode. The interfacial contact area “A” effectively is
`less than the overall surface area of the anode rods, as some
`rods oppose one another rather than the cathode.
`
`folded separator band can
`[0016] Also, a zig-zagged,
`define opposing compartments for holding and isolating
`plate-like cathode and anode electrodes, with electrolyte
`engulfing all of these components. In an alternative design,
`each cell can be formed with C-shaped electrodes and a
`Z-shaped separator sandwiched therebetween. Alternatively,
`a separator band having electrically conductive surfaces can
`be folded and sandwiched separate sets of respective plate-
`like cathode and anode electrodes between the separate
`oppositely facing folds. A “jellyroll” cell can be formed by
`coiling a preformed assembly of cathode and anode elec-
`trodes and a separator on itself,
`to yield a cylindrically
`shaped electrochemical device, with the face-to-face elec-
`trodes and sandwiched electrolyte and separator structures,
`increasing the interfacial contact area “A” between the
`electrodes.
`
`[0017] However, the very breadth of the facing electrodes
`and sandwiched electrolyte and separator raise another cause
`
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`US 2003/0013007 A1
`
`Jan. 16, 2003
`
`of concern, namely the structural sufficiency during assem-
`bly and during operation to maintain and support the elec-
`trode elements physically separated. This includes with-
`standing thermal expansion and contraction forces of the cell
`components during operational temperature changes, such
`as packing the cell into a box-like housing. Increasing the
`thickness of the sandwiched electrolyte and separator to
`provide needed strength and/or durability also increases the
`ion-conducting electrolyte thickness “1”, offsetting benefits
`obtained by increased interfacial contact area “A”.
`
`[0018] Current collectors used in these cell arrangements
`add significant weight, and thus reduced specific cell energy
`and power outputs. For example, isolated conductors are
`generally connected to the electrodes and routed along
`extended paths independently of the electrodes to the exter-
`nal
`terminals. These conductors must carry the full cell
`current, and thus must be of sufficient mass and cross-
`section to keep internal resistance manageably low. For a
`typical battery design of connected terminals, electrode
`tab/current collector/cell terminal resistance/battery termi-
`nal resistance can account for a 50% reduction in battery
`power output from theoretical capability. Generally, massive
`connectors are used to avoid power loss for high powered
`batteries.
`
`[0019] Also, these cell arrangements provide electrodes of
`limited size and/or thickness,
`limiting the quantities of
`usable electrode materials and thus limiting maximum cell
`storage energy and/or operating cycle-life, particularly for
`rechargeable cells.
`
`[0020] The dilemma of these designs is that power gains
`obtained by increasing the interfacial electrode area “A”
`across the electrolyte generally are typically offset by
`increased electrolyte thickness “1”, and the weight and
`volume of the current collectors reduce specific energy and
`power outputs. Power can be increased, but only at
`the
`expense of reduced energy storage capacity per weight and
`volume and at
`increased costs due to needed additional
`
`hardware. High interfacial area “A” of the spirally wound
`“jellyroll” configuration merely trades off usable power
`against the energy density; but minimum separator thickness
`is needed for cell durability and cycle-life. Existing bipolar
`cell arrangements do not escape this power and energy trade
`off dilemma; nor do fuel cell electrochemical devices.
`
`[0021] The rolled-ribbon cell technology disclosed in US.
`Pat. No. 5,219,673 has made great strides achieving
`enhanced power density for electrochemical devices. Spe-
`cifically applied to Li/organic-based electrolyte chemistries,
`improved batteries are formed using the stackable disk-
`shaped cells to realize near optimum power capability from
`these cells. Further objectives of batteries for high-pulse
`power requirement, such as hybrid electric vehicles and
`power tools,
`is to continue to reduce battery cost and
`increase durability. These Li/organic-based electrolyte bat-
`tery chemistries, although exhibiting quite high voltage (3-5
`volts), have relatively low current density capabilities. One
`limiting factor is the attempted use of relatively-thin com-
`ponents, i.e. the electrode and separator layers. A practical
`device requires a lot of active area. For example, with peak
`current density of 10 mA/cm2, it can require 1000 cm2 active
`area to achieve 10A. For hybrid electric vehicles,
`the
`required current is on the order of 100A at 200-400 volts
`(equivalent to 20-40 kW).
`
`[0022] A further dilemma is the large number of small
`cells required to form such batteries. A major power loss
`(internal heat generation) is the consequence of batteries
`with large numbers of small cells (e.g. 1 Ampere-hour (Ah)
`capacity as in the 18650 cell). More recently larger cells (10
`Ah) have used a prismatic configuration. These cells have
`broad electrodes with multiple tabs connected to a tradi-
`tional terminal connection. These prismatic cells are hard-
`wired together (terminal-to-terminal) in a rectangular box.
`Nonetheless, this arrangement of substantially larger cells
`can still sacrifice 50% of the theoretical power of the cell
`chemistry.
`
`[0023] However, previous button type cells, typically hav-
`ing very small capacity of 5-50 milli-Ah, lacked ease or
`consistency of battery assembly and/or distribution of high
`currents through the cell to the exterior terminals possibly
`due to the limited conductor paths of hardware components.
`A hybrid vehicle battery would require hundreds of thou-
`sands of these cells.
`
`[0024] Thus there is continuing and persistent need for
`electrochemical devices which have high energy density,
`provide high power output and approach the theoretical limit
`for electrical power output.
`
`[0025] A Li/organic-based electrolyte battery for high
`power applications, such as hybrid electric vehicle, must
`also incorporate features to enhance safety and battery
`longevity. As there are battery operation and degradation
`conditions that generate internal gas pressure, there needs to
`be noncatastrophic, cost effective means to relieve the gas
`pressure. The typical means is to include a rupture disc on
`the housing of the Li-ion cell. Rupture of a disc housing
`causes irreversible failure of that battery, and if a disc
`ruptures electrolyte may escape to further degrade the bat-
`tery.
`
`to long life of
`is critical
`[0026] Thermal management
`Li-ion batteries in retaining battery capacity particularly due
`to electrolyte degradation. Batteries capable of generating
`tens of kW must deal with a like amount of heat generation.
`Under high pulse power, heat is generated at the electrode/
`separator interface due to limited ionic conduction. For the
`conventional jelly-rolled cell, the most direct path for heat
`loss is across the layers of heat sensitive microporous
`polymer. Excessive temperature within the cell will locally
`shutdown the microporous polymer and higher temperatures
`result with further abuse. Excessive abuse can lead to
`
`auto-ignition of organic electrolyte.
`
`SUMMARY OF THE INVENTION
`
`In one embodiment, the present invention provides
`[0027]
`an electrochemical device made up of an electrode assembly
`which includes: (i) an elongated positive electrode with a
`first longitudinal edge; (ii) an elongated negative electrode
`with a first longitudinal edge; and (iii) a separation layer
`having a first longitudinal edge and a second longitudinal
`edge. In the electrochemical device the positive electrode,
`the separation layer, and the negative electrode are wound
`around a central axis thereby forming a coil of alternating
`electrode and separation layers such that the separation layer
`prevents direct contact between successive electrode layers.
`Additionally, the first longitudinal edge of the separation
`layer extends beyond the first
`longitudinal edge of the
`separation layer, and the first
`longitudinal edge of the
`
`VARTA EX. 2013 Page 12 of 23
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`

`US 2003/0013007 A1
`
`Jan. 16, 2003
`
`negative electrode extends beyond the second longitudinal
`edge of the separation layer. More effective use of expensive
`electrode coating provides several advantages, i.e. greater
`power output per weight of electrode. Cell power
`is
`increased by approximately twenty times relative to cell
`capacity. Cell hardware for the rolled-ribbon is a lesser
`portion of cell weight compared to the prismatic cell having
`terminal posts. Large intercell connection ( discs stacked
`face to face) effectively transmits power to the battery
`terminals.
`
`[0028] The electrochemical device can also include a
`housing having a positive terminal electrically coupled to
`the first longitudinal edge of the positive electrode and a
`negative terminal electrically coupled to the first longitudi-
`nal edge of the negative electrode, wherein the electrode
`assembly is enclosed by the housing, and an electrolyte
`adjacent to the electrode assembly and enclosed within the
`housing.
`
`[0029] The housing typically includes a first cup including
`the positive terminal and a second cup including the nega-
`tive terminal. In this manner the first cup and the second cup
`are joined together to form the housing such that the first and
`second cups are electrically isolated from one another and
`further wherein the positive terminal and negative terminal
`are generally planar.
`
`In another embodiment the housing seals the con-
`[0030]
`tents of the cell from the ambient atmosphere so that a
`pressure release component or feature can relieve the pres-
`sure build-up within the housing when the pressure within
`the housing reaches a predetermined limit, while leaving the
`cell operable after the pressure build-up within the housing
`is released.
`
`[0031] One or more of these electrochemical devices can
`be coupled together electronically in parallel or in series.
`When coupled, one of the electrode assemblies can provide
`a component for shorting the electrode assembly when the
`electrode assembly becomes nonoperative.
`
`In yet another embodiment housing of the device,
`[0032]
`which due to the electrode’s perpendicular orientation
`exhibits excellent heat rejection, includes channels which
`allow for a medium to circulate within, through or around
`the housing which further provides for cooling of the device.
`In the rolled-ribbon cell, the electrode foils act as cooling
`fins at the electrode/separator interface to draw heat out to
`the cell housing. The most direct path for heat loss is not
`across the layers of heat sensitive separation layer, but to the
`cell housing, which can be in contact with the cooling fluid.
`
`[0033] Still another embodiment of the device, the posi-
`tive electrode is not physically attached, such as metallur-
`gically welded together, to the positive terminal and nega-
`tive electrode is not metallurgically attached to the negative
`terminal.
`
`[0034] Another embodiment of the electrochemical device
`of the present invention combines an electrode assembly
`including:(i) an elongated positive electrode; (ii) an elon-
`gated negative electrode; and (iii) a separation layer, with a
`component coupled to the electrode assembly for shorting
`the electrode
`assembly when the electrode assembly
`becomes nonoperative. In this embodiment,
`the positive
`electrode, separation layer and the negative electrode are
`wound around a central axis forming a coil of alternating
`
`electrode and separation layers such that the separation layer
`prevents direct contact between successive electrode layers.
`This embodiment can also include a housing made up of a
`positive terminal electrically coupled to a first longitudinal
`edge of the positive electrode and a negative terminal
`electrically coupled to a first longitudinal edge of the nega-
`tive electrode, wherein the electrode assembly is enclosed by
`the housing. The housing also encloses an electrolyte. This
`embodiment can further include a pressure release compo-
`nent which relieves pressure build-up within the housing
`when the pressure within the housing reaches a predeter-
`mined limit, wherein the electrochemical device is still
`operable after the pressure build-up within the housing is
`released.
`
`In still another embodiment an electrochemical
`[0035]
`device comprising an electrode assembly in contact with an
`electrolyte, coupled to and enclosed by a housing which
`possesses the functionality of a pressure release component.
`The electrode assembly is made up of at least an elongated
`positive electrode, an elongated negative electrode and a
`separation layer wherein the positive electrode, the separa-
`tion layer, and the negative electrode are wound around a
`central axis thereby forming a coil of alternating electrode
`and separation layers such that the separation layer prevents
`direct contact between successive electrode layers. The
`electrode assembly is coupled to the housing, which has a
`positive terminal electrically coupled to a first longitudinal
`edge of the positive electrode and a negative terminal
`electrically coupled to a first longitudinal edge of the nega-
`tive electrode. The pressure release component relieves
`pressure build-up within the housing when the pressure
`within the housing reaches a predetermined limit, wherein
`the electrochemical device is still operable after the pressure
`build-up within the housing is released and the seal reseals
`itself. Internal gas pressure control is a safety feature that is
`achieved without jeopardizing the life expectancy of the
`battery. It is usually accomplished with rupture discs, which
`would cause the cell to be lost if ruptured. In the present
`invention, pressure release is accomplished with spring
`loading a stack of peripherally sealed cells. Because the
`cells, in essence, can burp to relieve gas pressure, they will
`reseal
`themselves. The seal configuration has enhanced
`exclusion of moisture infiltration/diffusivity with use of both
`polyethylene gasket and silicone fluid coolant. Because
`there is no added component to the cell, this design for
`internal pressure control is cost effective.
`
`[0036] The above described embodiments are set forth in
`more detail in the following description and illustrated in the
`drawings described hereinbelow.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0037] The preferred exemplary embodiment of the inven-
`tion will hereinafter be described in conjunction with the
`appended drawings, wherein like numerals denote like ele-
`ments and:
`
`[0038] FIG. 1 is a cut-away perspective view of the
`electrode/separation layer configuration in the electrode
`assembly of the present invention;
`
`[0039] FIG. 2 is a right side facial view showing the
`electrode assembly coiled on itself to define a rolled-ribbon
`cell (laminate cell membrane) of the type suited for forming
`an electrochemical device according to this invention;
`
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`

`US 2003/0013007 A1
`
`Jan. 16, 2003
`
`[0040] FIG. 3 depicts the process for making the elec-
`trode/separator assembly of the present invention;
`
`[0041] FIG. 4 is a cross-sectional view of the cell preas-
`sembly taken along line 4-4 of the process of FIG. 3;
`
`[0042] FIG. 5 is a cross-sectional view of the cell preas-
`sembly taken along line 5-5 of the process of FIG. 3;
`
`[0043] FIG. 6 is a cross-sectional view of the cell preas-
`sembly taken along line 6-6 of the process of FIG. 3;
`
`[0044] FIG. 7 depicts the housing for the electrochemical
`device of the present invention;
`
`[0045] FIG. 8 is a radial edge section of a bipolar elec-
`trochemical device incorporating the electrode assembly of
`the present invention;
`
`[0046] FIG. 9 shows a high voltage battery made up by
`stacking disc-shaped electrochemical cells of the present
`invention, along with a cross-sectional view and a detailed
`cross-sectional view of the high voltage battery, taken along
`line 9-9; and
`
`[0047] FIG. 10 depicts an embodiment of the present
`invention that can achieve greater cooling of the electro-
`chemical cells.
`
`[0048] FIG. 11, depicts an arrangement of electrode and
`cell hardware that is conducive of internal heat rejection,
`where negative electrode (bottom) and positive electrode
`(top) communicate with opposite faces of cell hardware to
`remove heat from separator interface (typically Celgard).
`
`[0049] FIG. 12, depicts the skin temperature monitoring
`of rolled-ribbon cell during HPPC Tests (60A discharge
`pulse)
`
`[0050] FIG. 13 depicts a plot of cell temperature (5 Ah)
`from constant power full discharge at 75W and 100W, or 6C
`and 8C rates.
`
`[0051] FIG. 14 depicts a Ragone plot, comparing the
`specific energy of the rolled ribbon cell with a spiral wound
`Li-ion cell at high power Output (25° C.)
`
`[0052] FIG. 15, depicts a cell voltage and current plot vs.
`time for a cell undergoing a 100A (20 C rate) 18 sec
`discharge.
`
`[0053] FIG. 16, depicts a plot of Flat Cell Resistance vs.
`State of Charge (from HPPC-High test) demonstrating
`expansion of usable cell capacity (5 Ah)
`
`[0054] FIG. 17 depicts a current vs. time profile for a cell
`pulsed at 180A (35C rate) to provide in excess of 500W for
`2.4 kW/kg peak specific power for these cells.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`[0055] The present invention provides an improved cell
`arrangement involving the orientation of positive and nega-
`tive electrodes, interpositioned separator and/or electrolyte,
`and current collectors used in making up the electrochemical
`device. The improved cell uses an electrode assembly with
`laminated
`electrode/foils
`comprised
`of
`alternatively
`arranged, generally parallel, positive and negative elec-
`trodes, and a separator layer and/or electrolyte formed of a
`very thin ionic-conductive ribbon-like layer configured in a
`tight serpentine manner and physically interposed between
`
`the electrodes. This basic laminate cell preassembly is
`layered on itself, such as by winding or coiling it as a spiral
`to form an electrode assembly, in the general shape of a flat
`disc (wherein the diameter is preferably greater than twice
`the thickness of the disk) and the cell membrane is sand-
`wiched between plate-like current collectors with the elec-
`trode interfaces primarily perpendicular to the current col-
`lectors, to make up an electrochemical cell.
`
`[0056] Because of the expense of lithium ion batteries,
`which also provide the greatest electrochemical potential
`and largest energy content, the rolled-ribbon cell configu-
`ration of the present invention has particular utility for cells
`employing
`lithium/organic
`electrolyte
`cell
`chemistry,
`although the present invention is also well suited to other
`cell chemistries, including, but not limited to, nickel/metal
`hydride and alkaline electrolyte systems. Of a particular
`interest, the technology provides high pulse power devices,
`at reduced costs and with excellent thermal management
`producing kW levels of power.
`
`[0057] The improved cell arrangement of the present
`invention uses a ribbon-like cell assembly, with coated foil
`electrode strips extending beyond the edge of the folded
`separator when viewed in cross section. The extended elec-
`trode areas can have lesser or no active electrode material
`
`and the electrode ribbons are preferably cored with metal
`foils or other electron conducting material e.g. carbon paper
`and/or electrically conductive polymer. For a 5 inch diam-
`eter cell, 100 to 250 ft of electrode edge contact with a cell
`housing is typically achieved.
`
`[0058] The invention provides for adding electrode mate-
`rial or cell capacity by way of extending the electrode strips
`beyond the separation layer. Rather than having electrode
`discs applied to the major faces of the rolled-ribbon cell or
`cell separator membrane as in earlier button type electro-
`chemical cells, the electrode extensions define reservoirs of
`electrode material. These extensions are subsequently com-
`pacted into a disc as the cell is assembled into the disc
`enclosure hardware.
`
`[0059] The invention also provides for a separator ribbon
`configuration in which the folds of the separation layer are
`oriented up and down at each edge. This arrangement serves
`to align the electrode ribbons with respect to the separator
`and helps to ensure the positioning of the electrodes and
`separator during the cell winding operation. This alignment
`aids in forming a flat disc cell.
`
`[0060] The invention can provide an electronic compo-
`nent, which can serve to electrically remove a shorted or
`defective cell. Preferably the electronic component
`is
`embedded within the cell and preferably resides within at the
`center hub of the cell for ease of manufacture, for example
`by initiating the cell winding. In a preferred embodiment a
`diode is utilized for removing (or short-circuiting) the non-
`operative cell. Similarly, the component can act to bypass
`current at overcharge or excessive voltage conditions.
`
`[0061] The invention also provides a button-type cell
`enclosure. Consisting of two opposing shallow cups, which
`are electrically isolated from each other with a polymeric
`“U” shaped gasket at the outer edge. The gasket further
`forms a gas-tight seal for the interior contents of the cell.
`These cups members interface with the perpendicular elec-
`trode member of another electrochemical cell to serve as
`
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`US 2003/0013007 A1
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`Jan. 16, 2003
`
`both a current collector and a cell terminal. The positive
`electrode substrate is essentially of the same material as the
`positive terminal surface and the negative electrode sub-
`strate is essentially of the same material as the negative
`terminal surface. The positive is generally aluminum and the
`negative is generally copper.
`
`[0062] The invention also provides a high voltage and
`high capacity battery assembled by stacking a plurality of
`button-type cells together. The cells are typically connected
`in series. Control of internal gas pressure and maintenance
`of contact pressure between the button cell in the stack can
`be accomplished with active pressure, such as a Belleville
`spring washer. The specified limit for internal pressure is
`handled by release via the peripheral seal, which can reseal
`after an event.
`
`[0063] The invention also provides for an augmentation of
`passive thermal management of the high power battery by
`manifolding cooling fluid about
`the battery stack and
`between the disc-shaped cells. A thermostated control
`pumps the fluid to external cooling such as radiator or small
`refrigeration unit. The cell hardware pans of the button-type
`battery enclosures conduct heat from the electrode/separator
`interface. Further, via flow passages between the faces o