Bipolar electrochmeical battery of stacked wafer cells

• US 5,393,617 A
• Filed: 10/08/1993
• Issued: 02/28/1995
• Est. Priority Date: 10/08/1993
• Status: Expired due to Term

• Current Assignee: Electro Energy, Inc. (Delaware)
• Original Assignee: Electro Energy, Inc. (Delaware)
• Inventors: Klein, Martin
• Primary Examiner(s): Maples, John S.
• Application Number:
  US08/134,429
• Time in Patent Office: 508 Days
• Field of Search: 429/153, 429/157, 429/158, 429/162, 429/59, 429/223, 429/224, 429/90, 429/220, 429/217, 429/210
• US Class Current: 429/59
• CPC Class Codes: H01M 10/0413 Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes
• CPC Class Codes: H01M 10/0418 with bipolar electrodes
• CPC Class Codes: H01M 10/0468 Compression means for stacks of electrodes and separators
• CPC Class Codes: H01M 10/24 Alkaline accumulators
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/526 by gas recombination on the electrode surface or by structuring the electrode surface to improve gas recombination
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2004/029 Bipolar electrodes
• CPC Class Codes: H01M 4/0435 Rolling or calendering
• CPC Class Codes: H01M 4/24 Electrodes for alkaline accumulators
• CPC Class Codes: H01M 4/242 Hydrogen storage electrodes
• CPC Class Codes: H01M 4/26 Processes of manufacture
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/383 Hydrogen absorbing alloys
• CPC Class Codes: H01M 4/385 of the type LaNi5
• CPC Class Codes: H01M 4/48 of inorganic oxides or hydroxides
• CPC Class Codes: H01M 4/481 of mercury
• CPC Class Codes: H01M 4/50 of manganese
• CPC Class Codes: H01M 4/52 : of nickel, cobalt or iron
• CPC Class Codes: H01M 4/54 : of silver
• CPC Class Codes: H01M 4/622 : being polymers
• CPC Class Codes: H01M 4/623 : fluorinated polymers
• CPC Class Codes: H01M 4/624 : Electric conductive fillers
• CPC Class Codes: H01M 4/626 : Metals
• CPC Class Codes: H01M 4/808 : Foamed, spongy materials
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49108 : Electric battery cell making
• CPC Class Codes: Y10T 29/49115 : including coating or impregnating

Abstract

The subject invention relates to electrode structures that are adaptable for primary and electrically rechargeable electrochemical wafer cells. A flat wafer cell is disclosed that includes conductive, carbon-filled polymeric outer layers that serve as electrode contacts and as a means of containment of the cell. Multi-cell, higher voltage batteries may be constructed by stacking individual cells. Specially formulated electrodes and processing techniques that are compatible with the wafer cell construction are disclosed for a nickel-metal hydride battery system. The cell design and electrode formulations provide for individual operation of a vented or low pressure sealed cell and/or for operation of these cells in a stacked array in an outer battery housing.

Claims

1. A bipolar electrochemical battery comprising:

a stack of at least two electrochemical cells electrically arranged in series wherein the adjacent cells have a positive face of one cell contacting a negative face of the adjacent cell, wherein each of said cells contains

(a) a metal hydride electrode;

(b) a nickel electrode;

(c) a porous separator between said electrodes, wherein said separator contains an electrolyte;

(d) a first electrically conductive outer layer in electrical contact with the outer face of said metal hydride electrode; and

(e) a second electrically conductive outer layer in electrical contact with the outer face of said nickel electrode;

wherein said outer layers are sealed peripherally to an electrically non-conductive polymeric material such as to form a sealed enclosure containing said electrodes, said separator and said electrolyte.

2. The bipolar electrochemical battery of claim 1 wherein said electrodes, said separator and said outer layers are each substantially flat.

3. The bipolar electrochemical battery of claim 1 wherein said metal hydride electrode contains metal hydride particles embedded in an interconnected network of binder material, wherein said binder material comprises from about 0.5 to about 5 weight percent of the total electrode weight.

5. The bipolar electrochemical battery of claim 1 wherein said metal hydride electrode contains copper.

6. The bipolar electrochemical battery of claim 5 wherein said copper is present as metallic copper.

7. The bipolar electrochemical battery of claim 6 wherein said metallic copper forms an interconnected thin metallic layer on said metal hydride particles.

8. The bipolar electrochemical battery of claim 1 wherein said electrically-conductive, outer layers comprise carbon-filled polymeric film.

9. The bipolar electrochemical battery of claim 1 wherein said electrically non-conductive polymeric material comprises a vinyl polymer.

10. The bipolar electrochemical battery of claim 9 wherein said outer layers are heat sealed to said vinyl polymer.

11. The bipolar electrochemical battery of claim 1 wherein said nickel electrode is a pasted foam nickel electrode.

12. The bipolar electrochemical battery of claim 1 wherein a conductive paste or cement is present between at least one of said outer layers and said electrode with which it is in contact.

13. The bipolar electrochemical battery of claim 1 wherein a conductive porous spacer is between said metal hydride electrode and said conductive outer layer.

14. The bipolar electrochemical battery of claim 13 wherein said porous spacer comprises porous graphite paper.

15. The bipolar electrochemical battery of claim 13 wherein the side of said metal hydride electrode facing said porous spacer is wet proofed.

16. The bipolar electrochemical battery of claim 13 wherein the side of said metal hydride electrode facing said porous spacer is provided with a catalyst for enhancing recombination of oxygen or hydrogen.

17. The bipolar electrochemical battery of claim 1 wherein said stack of at least two electrochemical cells is contained in a sealed battery housing.

18. The bipolar electrochemical battery of claim 17 wherein a pressure measuring device is included in said sealed battery housing.

19. The bipolar electrochemical battery of claim 17 wherein each electrochemical cell is completely sealed, wherein said battery housing contains an electrically non-conductive fluid that substantially fills the void space around said stack of cells and wherein a pressure measuring device is included in said battery housing.

20. The bipolar electrochemical battery of claim 17 wherein a conductive past or cement is present between said cells.

21. The bipolar electrochemical battery of claim 17 wherein at least one of the end cells of said stack of cells is in contact with a metal foil, wherein said metal foil is electrically connected to a battery terminal.

22. The bipolar electrochemical battery of claim 17 wherein a conductive paste or cement is present between at least one of said end cells and said metal foil.

23. The bipolar electrochemical battery of claim 17 wherein said stack of cells is held in compression by means of tie rods that penetrate through sealed holes in the electrochemical cells.

24. The bipolar electrochemical battery of claim 17 wherein said stack of cells are held in compression by means of a layer of sponge rubber.

25. The bipolar electrochemical battery of claim 17 wherein said stack of cells are held in compression by means of a spring.

26. The bipolar electrochemical battery of claim 17 wherein said stack of cells are held in compression by means of a gas-filled compressible pad.

27. The bipolar electrochemical battery of claim 17 wherein said electrochemical cells include vent ports.

4. The bipolar electrochemical battery of 3 wherein said binder material comprises polytetrafluoroethylene.

28. A metal hydride electrode comprising:

a mixture of metal hydride particles and cupric oxide particles, wherein said mixture is embedded in an interconnected network of polytetrafluoroethylene, wherein said interconnected network containing said mixture forms an electrode and wherein said polytetrafluoroethylene comprises from about 0.5 to about 5.0 weight percent of the electrode weight.

29. The metal hydride electrode of claim 28 wherein said electrode is substantially flat.