Energy storage device and its methods of manufacture

• US 5,711,988 A
• Filed: 01/23/1995
• Issued: 01/27/1998
• Est. Priority Date: 09/18/1992
• Status: Expired due to Term

• Current Assignee: Ultracap Technologies Corp.
• Original Assignee: Pinnacle Research Institute, Inc.
• Inventors: Goodwin, Mark L., Tsai, K. C., Mason, Gary E.
• Primary Examiner(s): LUSIGNAN, MICHAEL R
• Application Number:
  US08/377,121
• Time in Patent Office: 1,100 Days
• Field of Search: 29/25.03, 29/25.01, 361/503, 361/305, 427/80, 427/282
• US Class Current: 427/80
• CPC Class Codes: H01G 11/12 Stacked hybrid or EDL capacitors
• CPC Class Codes: H01G 11/26 characterised by their structure, e.g. multi-layered, porosity or surface features
• CPC Class Codes: H01G 11/80 Gaskets; Sealings
• CPC Class Codes: H01G 11/82 Fixing or assembling a capacitive element in a housing, e.g. mounting electrodes, current collectors or terminals in containers or encapsulations
• CPC Class Codes: H01G 11/84 Processes for the manufacture of hybrid or EDL capacitors, or components thereof
• CPC Class Codes: H01M 10/0418 with bipolar electrodes
• CPC Class Codes: H01M 4/00 Electrodes
• CPC Class Codes: H01M 4/04 Processes of manufacture in general
• CPC Class Codes: H01M 4/0402 Methods of deposition of the material
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0409 by a doctor blade method, slip-casting or roller coating
• CPC Class Codes: H01M 4/0416 involving impregnation with a solution, dispersion, paste or dry powder H01M4/0438 takes precedence
• CPC Class Codes: H01M 4/0419 involving spraying
• CPC Class Codes: H01M 4/0428 Chemical vapour deposition
• CPC Class Codes: H01M 4/0438 by electrochemical processing electroless electrochemical plating C23C18/54
• CPC Class Codes: H01M 4/045 Electrochemical coating; Electrochemical impregnation
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/58 of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
• CPC Class Codes: H01M 50/184 characterised by their shape or structure
• CPC Class Codes: H01M 50/186 characterised by the disposition of the sealing members
• CPC Class Codes: H01M 50/193 : Organic material
• CPC Class Codes: H01M 50/198 : characterised by physical properties, e.g. adhesiveness or hardness
• CPC Class Codes: H01M 50/46 : Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: H01M 50/557 : Plate-shaped terminals
• CPC Class Codes: H01M 50/627 : Filling ports
• CPC Class Codes: H01M 6/48 : with bipolar electrodes
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/13 : Energy storage using capacitors
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

A dry preunit (10), includes a plurality of cells (110, 112, 114) in a true bipolar configuration, which are stacked and bonded together, to impart to the device an integral and unitary construction. Each cell (114) includes two electrically conductive electrodes (111A, 111B) that are spaced apart by a predetermined distance. The cell (114) also includes two identical dielectric gaskets (121,123) that are interposed, in registration with each other, between the electrodes (111A, 111B), for separating and electrically insulating these electrodes. When the electrodes (111A, 111B), and the gaskets (121, 123) are bonded together, at least one fill gap (130) is formed for each cell. Each cell (114) also includes a porous and conductive coating layer (119, 120) that is formed on one surface of each electrode. The coating layer (119) includes a set of closely spaced-apart peripheral microprotrusions (125), and a set of distally spaced-apart central microprotrusions (127). These microprotrusions (125, 127) impart structural support to the cells, and provide additional insulation between the electrodes. An energy storage device (10A) such as a capacitor, is created with the addition of an electrolyte to the gap (130) of the dry preunit (10) and subsequent sealing of the fill ports.

Claims

1. A method of producing an array of substantially uniform microprotrusions on a surface as a separator useful in the construction of single or multiple layer electrical charge storage devices, which method comprises:

(a) obtaining an electrically insulating material which is essentially inert to electrolyte conditions to produce a thixotropic composition at between ambient temperature to about 75°

C. and ambient pressure;

(b) obtaining a thin electrode material comprising a thin flat electrically conducting metal sheet center coated on one or both sides with electrically conducting carbon, porous metal oxide, porous mixed metal oxide or other porous coating and securing the flat electrode in a suitable holder;

(c) placing a thin flat screen or stencil having small openings over the flat thin electrode;

(d) contacting the top exterior thin screen surface with the flowable composition of step(a) so that small portions of the composition extrude through the pattern and contact the exterior surface of the thin electrode and optionally penetrate the exterior surface of the porous electrode coating, when a squeegee is brought across the screen surface to cause contact of the screen with the electrode surface;

(e) removing the sample from the screen printer; and

(f) curing the applied material whereby the discrete microprotrusions essentially retain their shape and dimensions.

2. An improved method to produce a dry preunit of an electrical storage device for storage of electrical charge in a condition to have the electrode surfaces contacted with a non-aqueous or aqueous electrolyte, which method comprises:

(a) preparing a thin in thickness substantially flat sheet of electrically conducting support material coated on each flat side with the same or different thin layer of a second electrically conducting material having a high surface area, optionally with the provision that both flat sides of the electrically conducting support is a sheet having the perimeter edge surfaces either;

(i) having a thin layer of second electrically conducting material,

(ii) are partly devoid of second electrically conducting material, or

(iii) are devoid of second electrically conducting material;

(b) creating an ion permeable or semipermeable space separator stable to the aqueous or non-aqueous electrolyte obtained by;

(i) depositing substantially uniform in height groups of electrically insulating microprotrusions, on the surface of at least one side of the thin layer of second electrically conducting material,

(ii) placing a thin precut ion permeable or semipermeable separator on one surface of the second electrically conducting material, or

(iii) casting an ion permeable or semipermeable thin layer on the surface of at least one side of the electrically conducting material, or

(iv) creating a thin air space as separator;

(c) contacting the perimeter edge surface of one or both sides of the thin sheet of step (b) with one or more thin layers of synthetic organic polymer as a gasket material selected from the group consisting of a thermoplastic, thermoelastomer, and a thermoset polymer;

(d) placing on or within the gasket material and optionally across the thin sheet at least one thin cord of a different material which cord has a higher melting point (T_m) greater than the gasket polymer material and does not melt, flow, or permanently adhere to the gasket under the processing conditions;

(e) producing a repeating layered stack of the thin flat articles of sheet coated with high surface area coating and separator produced in step (d) optionally having the end sheets consisting of a thicker support;

(f) heating the stack produced in step (e) at a temperature and applied pressure effective to cause the synthetic gasket material to flow, to adhere to, and to seal the edges of the stack creating a solid integral stack of layers of alternating electrically conductive sheet coated with second electrically conducting material and the ion permeable separator, optionally such that the gasket material creates a continuous integral polymer enclosure;

(g) cooling the solid integral stack of step (f) optionally in an inert gas under slight pressure; and

(h) removing the at least one thin cord of different material between each layer creating at least one small opening between the layers of electrically conducting sheet coated with second electrically conducting material.

3. The method of claims 2, wherein either after step (e) and before step (f) or after step (h), the integral stack is treated by:

(j) evacuating the dry preunit to substantially remove residual gases;

(k) contacting the dry unit with one or more reducing gases at near ambient pressure;

(l) heating the unit and reducing gas to between about 20°

to 150°

C. for between about 0.1 and 5 hr;

(m) evacuating the dry preunit;

(n) replacing the reducing atmosphere with inert gas; and

(o) optionally repeating steps (j), (k), (l), (m), and (n) at least once.

4. The method of claim 2, wherein either after step (e) and before step (f) or after step (h), the integral stack is treated by:

(j) evacuating the dry preunit to substantially remove residual gases;

(k) contacting the dry unit with one or more reducing gases at near ambient pressure;

(l) heating the unit and reducing gas to between about 20°

to 150°

C. for between about 0.1 and 5 hr;

(m) evacuating the dry preunit;

(n) replacing the reducing atmosphere with inert gas; and

(o) optionally repeating steps (j), (k), (l), (m), and (n) at least once.

5. An improved method to produce a dry preunit or an electrical storage device for storage of electrical charge in a condition to have the electrode surfaces contacted with a non-aqueous or aqueous electrolyte, which method comprises:

(a) obtaining a thin in thickness flat metal sheet support wherein the metal is selected from titanium, tantalum, niobium, zirconium, iron, copper, lead, tin, nickel, zinc or combinations thereof, having a thickness of between about 0.1 and 10 mil coated on each flat surface with a thin porous layer of at least one metal oxide having a high surface area independently selected from metal oxides of the group consisting of tin, lead, vanadium, titanium, ruthenium, tantalum, rhodium, osmium, iridium, iron, cobalt, nickel, copper, molybdenum, niobium, chromium, manganese, lanthanum or lanthanum series metals or alloys or combinations thereof, possibly containing small percentage of additives to enhance electrical conductivity,

wherein the thin metal oxide layer has a thickness of between about 0.1 and 200 microns,

optionally with the provision that both flat surfaces of the electrically conducting sheet have the perimeter edge surfaces devoid of metal oxide;

(b) creating an ion permeable space separator which is stable to the aqueous or non-aqueous electrolyte selected from;

(i) depositing a substantially uniform in height array of electrically insulating discrete microprotrusions which are stable to an aqueous or non-aqueous electrolyte having a height of between about 0.1 and 10 mil on the surface of one or both sides of the thin layer of porous metal oxide,

(ii) placing a thin precut ion permeable electrically insulating separator having a thickness of between about 0.1 and 10 mil on one flat surface of the metal oxide layer;

(iii) casting an ion permeable or semipermeable separator having a thickness of between about 0.1 and 10 mil on at least one surface of the second electrically conducting material;

or

(iv) creating a thin air space as a separator;

(c) contacting the perimeter edge surface of one or both sides of the thin electrically conducting sheet of step (b) with one or more thin layers of synthetic organic polymer as a gasket material wherein the polymer is selected from the group consisting of polyimides, a polytetrafluoroethylene-trifluoroethylene copolymer, styrene-butadiene copolymer, polyethylenes, polypropylenes, polyolefins, polysulfone, fluorinated polymers, partly fluorinated polymers and combinations thereof;

(d) placing on or within the gasket material and optionally across the thin flat sheet at least one thin cord of a different material which has a higher melting temperature (T_m) than the polymeric gasket material, which cord does not melt, flow or adhere to the gasket material under the processing conditions described herein;

(e) assembling a repeating layered stack of the thin flat articles of sheet coated with metal oxide and separator produced in step (d) optionally having end sheets having only one side coated and/or being made of thicker support material;

(f) heating the layered stack of step (e) at about 5°

to 100°

C. greater than T_m of the gasket material causing the gasket material to flow, to adhere to, and to seal the edges of the layered stack creating a solid integral layered stack of sheet and separator optionally enclosing and sealing the stack in an integral polymer enclosure;

(g) cooling to ambient temperature the solid integral stack of step (f) in an inert environment; and

(h) removing the at least one thin cord between each layer creating at least one small opening into the fill gap located between the porous electrode layers.

6. The method according to claim 5, wherein:

in step (a) the support has second electrically conducting material on the perimeter edge surfaces,

in step (b) the microprotrusions are on the surface of the second electrically conducting material,

in step (c) the gasket material is a thermoplastic,

in step (e) the end sheets are a thicker support material,

in step (f) the gasket material is in excess to create a continuous integral enclosure,

in step (g) the stack is cooled to ambient temperature,

in step (h) the cord comprises a metal, ceramic, organic polymer or combinations thereof.

7. The energy storage device obtained by using the preunit device according to claim 5 and

adding an electrolyte to fill the evacuated fill gap regions,

sealing the fill port openings, and

electrically charging the electrical storage device wherein said device has uses as an electrical source of power for applications independently selected from:

providing peak power in applications of varying power demands and be recharged during low demand (i.e. serving as means for a power conditioner, placed between the electrical generator and the electrical grid of the users;

providing power in applications where the electrical source may be discontinued and additional power is needed to power in the interim period or for a period to allow for a shutdown providing means for uninterruptable power source applications, comprising computer memory shutdown during electrical grey and brown outs, or power during periodic black outs as in orbiting satellites;

providing pulse power in applications requiring high current and/or energy comprising means for a power source to resistively heat catalysts, to power a defibrillator or other cardiac rhythm control device, or to provide pulse power in electric vehicle where in a battery or internal combustion engine could recharge the device;

providing power in applications that require rapid recharge with prolonged energy release comprising surgical instruments with out an electrical cord;

or

providing a potable power supply for appliance and communication applications.

8. An energy storage device according to claim 5 further including an ionically conductive fluid medium, within the cell gaps of the dry preunit, wherein the fill ports are sealed.

9. The further inclusion of porous hydrophobic polymeric material within the fill gap of each cell during construction of claim 5 to mitigate the increase of hydrostatic pressure with an increase in temperature.

10. The porous hydrophobic polymeric material of claim 9 wherein the material comprise polytetrafluoroethylene and has water entrance pressures of between 760 and 7600 torr.

11. The method of claim 5 wherein the screen printable material is a thermal or photo-curable epoxy resin.

12. The method of claim 5 wherein

in step (a) the porous electrode formed is conditioned by contact with:

(a) steam at a temperature of between about 150° and

300°

C. for between about 0.5 and 4 hr,

(b) a reactive gas or a reactive liquid at a temperature of between about 80°

to 140°

C. for between about 0.2 and 2 hr, or

(c) an anodic current sufficient to evolve oxygen for between about 1 to 60 min,

then contacted with a cathodic current without hydrogen gas evolution until the open circuit potential is adjusted to between about 0.5V to 0.75V (vs. normal hydrogen electrodes.

13. The method of claim 5 after step (c) between steps (d) and (e) conditioning the porous coating by

contact with a cathodic current until the open circuit potential is adjusted to between about 0.5V to 0.75V (vs. normal hydrogen electrode).

14. The method of claim 5 wherein

in step (a), the support is titanium, tantalum or niobium, the mixed metal oxides are ruthenium and tantalum having a thickness of between about 5 and 25 microns, wherein the perimeter edges of the porous electrode are contacted with a dilute solution of a styrene-butadiene/ethylene copolymer in a non-aqueous organic solvent, and dried to seal the edges to insure electrical isolation of the cell;

in step (b), the separator is multiple microprotusions;

in step (c), the gasket material is-selected from the group consisting of a styrene-butadiene copolymer and high density polyethylene; and

in step (d), the pull cord is a polytetrafluoroethylene-trifluoroethylene copolymer.

15. An improved method to produce an electrical storage device for storage of electrical charge, which method comprises:

evacuating the dry preunit produced by the method of claim 5,

contacting the evacuated dry preunit with an electrolyte selected from either an aqueous inorganic acid or a non-aqueous organic ionically conducting medium for a time sufficient to backfill the space between the support sheets using the fill port,

removing any exterior surface electrolyte, and

closing and sealing the fill port openings.

16. A method to produce a sealable and electrically insulating band of organic polymer on the perimeter edges of an individual electrode for use in an energy storage device of claim 5, which method comprises:

A. obtaining a thin flat electrode comprising a thin porous oxide coated on a thin electrode substrate with or without insulating separators applied to one or both of the flat porous oxide surfaces;

B. dissolving at least one organic polymer in at least one organic solvent to obtain a solution having a viscosity of between about 300 and 3000 centipoise;

C. coating the edge perimeter of each of the flat electrode Wherein the total surface area of organic polymer on one side covers between about 5 and 25% of the total area of the flat surface of one side of the electrode from each perimeter edge to create a continuous substantially uniform edge coating of organic polymer having a thickness of between about 0.1 to 0.5 mil; and

D. removing at least one organic solvent from the organic polymer edge coating by maintaining the coated electrode at ambient temperature and pressure for between about 0.1 and 1000 min followed by heating at between about 80° and

150°

C. for between about 0.1 and 10 hr, optionally under vacuum conditions.

17. The method of claim 16 wherein the thermoplastic elastomer comprises, a styrene-butadiene copolymer.