Methods of fabricating electrochemical cells

• US 5,894,656 A
• Filed: 04/11/1997
• Issued: 04/20/1999
• Est. Priority Date: 04/11/1997
• Status: Expired due to Fees

• Current Assignee: Valence Technology Incorporated (Lithium Werks B.V.), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Inventors: Rundle, Wayne T., Menon, Krishna
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US08/840,089
• Time in Patent Office: 739 Days
• Field of Search: 429/162, 429/251, 429/253, 429/254, 29/623.5
• US Class Current: 29/623.1
• CPC Class Codes: H01M 10/0436 Small-sized flat cells or batteries for portable equipment
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2300/0085 Immobilising or gelification of electrolyte
• CPC Class Codes: H01M 50/46 Separators, membranes or diaphragms characterised by their combination with electrodes
• CPC Class Codes: H01M 6/16 with organic electrolyte H01M6/18 takes precedence
• CPC Class Codes: H01M 6/181 with polymeric electrolytes
• CPC Class Codes: H01M 6/188 Processes of manufacture
• CPC Class Codes: H01M 6/40 Printed batteries , e.g. thin film batteries
• 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

Abstract

Electrochemical cells with improved adhesion of the laminant components can be fabricated by forming an electrode directly on the surface of electrolyte or separator film. This process obviates the need to prepare the anode or cathode in a separate procedure.

Claims

1. A method of preparing an electrode/separator assembly that comprises the steps of:

(a) preparing a polymer mixture comprising a first polymer, a first polymer solvent, and a first plasticizer;

(b) applying a layer of the polymer mixture onto a first substrate and removing first polymer solvent from the layer of polymer mixture to form a coated substrate having a first polymer matrix film coated on the first substrate;

(c) preparing an electrode mixture comprising an electrode active material, a second polymer, a second polymer solvent, and a second plasticizer;

(d) applying a layer of the electrode mixture onto the first polymer matrix film and removing second polymer solvent from the layer of electrode mixture to form a first electrode/separator bi-layer having a first electrode film coated on the first polymer matrix film; and

(e) attaching a current collector onto the first electrode film.

2. The method of claim 1 wherein the polymer mixture includes an inert filler material.

3. The method of claim 1 wherein the electrode active material is an anode active material comprising an intercalation carbon material.

4. The method of claim 3 wherein the intercalation carbon material is selected from the group consisting of graphite, coke, mesocarbon, and mixtures thereof.

5. The method of claim 1 wherein the electrode active material is a cathode active material.

6. The method of claim 5 wherein the cathode active material is selected from lithiated manganese oxides, lithiated cobalt oxides, lithiated nickel oxides, and mixtures thereof.

7. The method of claim 1 wherein the first and second polymer solvents comprise acetone.

8. The method of claim 1 wherein the first and second polymers comprise a copolymer of vinylidenedifluoride and hexafluoropropylene.

9. The method of claim 1 wherein the substrate is a film or non-woven web made from material selected from the group consisting of paper, polyester, polypropylene, and polyethylene.

10. The method of claim 1 further comprising forming a second electrode/separator bi-layer comprising a second electrode film that is coated onto a second polymer matrix film by repeating steps (b) through (d), and then attaching the second polymer matrix film onto said current collector.

11. The method of claim 10 wherein the electrode active material is an anode active material comprising an intercalation carbon material.

12. The method of claim 11 wherein the intercalation carbon material is selected from the group consisting of graphite, coke, mesocarbon, and mixtures thereof.

13. The method of claim 10 wherein the electrode active material is a cathode active material.

14. The method of claim 13 wherein the cathode active material is selected from lithiated manganese oxides, lithiated cobalt oxides, lithiated nickel oxides, and mixtures thereof.

15. The method of claim 10 wherein the first and second polymer solvents comprise acetone.

16. The method of claim 10 wherein the first and second polymers comprise a copolymer of vinylidenedifluoride and hexafluoropropylene.

17. The method of claim 10 wherein the first substrate is a film or non-woven web made from material selected from the group consisting of paper, polyester, polypropylene, and polyethylene.

18. A method of fabricating an electrochemical cell comprising the steps of:

(a) preparing an anode by a process comprising;

(i) preparing a polymer mixture comprising a first polymer, a first polymer solvent, and a first plasticizer;

(ii) applying a layer of the polymer mixture onto a first substrate and removing first polymer solvent from the layer of polymer mixture to form a coated substrate having a first polymer matrix film coated on the first substrate;

(iii) preparing an anode mixture comprising an anode active material, a second polymer, a second polymer solvent, and a second plasticizer;

(iv) applying a layer of the anode mixture onto the first polymer matrix film and removing second polymer solvent from the layer of anode mixture to form a first anode/separator bi-layer having a first anode film coated on the first polymer matrix film;

(v) attaching an anode current collector onto the first anode film;

(vi) repeating steps (ii) through (iv) to form a second anode/separator bi-layer having a second polymer matrix film that is coated on a first side with a second anode film and that is coated on the second side with a second substrate; and

(vii) attaching said anode current collector onto the second anode film to form an anode comprising an anode current collector having two sides wherein one side is attached to the first anode film of the first anode/separator bi-layer and the other side is attached to the second anode film of the second anode/separator bi-layer;

(b) preparing a cathode by a process comprising;

(i) applying a layer of the polymer mixture onto a second substrate and removing first polymer solvent from the layer of polymer mixture to form a coated substrate having a third polymer matrix film coated on a third substrate;

(ii) preparing a cathode mixture comprising a cathode active material, a third polymer, a third polymer solvent, and a third plasticizer;

(iii) applying a layer of the cathode mixture onto the third polymer matrix film and removing third polymer solvent from the layer of cathode mixture to form a first cathode/separator bi-layer having a first cathode film coated on the third polymer matrix film;

(iv) attaching a cathode current collector onto the first cathode film;

(v) repeating steps (i) through (iv) of step (b) to form a second cathode/separator bi-layer having a fourth polymer matrix film that is coated on a first side with a second cathode film and that is coated on the second side with a fourth substrate; and

(vi) attaching said cathode current collector onto the second cathode film to form a cathode comprising a cathode current having two sides wherein one side is attached to the first cathode film of the first cathode/separator bi-layer and the other side is attached to the second cathode film of the second cathode/separator bi-layer;

(c) adding an electrolyte solution comprising an electrolyte solvent and a salt into the first, second, third and fourth polymer matrix films;

(d) removing the substrate from the first polymer matrix film and the third substrate from the third polymer matrix film; and

(e) attaching the first polymer matrix film to the third polymer matrix film.

19. The material of claim 18 wherein the polymer mixture includes an inert filler material.

20. The method of claim 18 wherein the anode active material comprising an intercalation carbon material.

21. The method of claim 20 wherein the intercalation carbon material is selected from the group consisting of graphite, coke, mesocarbon, and mixtures thereof.

22. The method of claim 21 wherein the cathode active material is selected from lithiated manganese oxides, lithiated cobalt oxides, lithiated nickel oxides, and mixtures thereof.

23. The method of claim 18 wherein the first, second, third, and fourth polymer solvents comprise acetone.

24. The methaod of claim 18 wherein the first, second, third, fourth polymers comprise a copolymer of vinylidenedifluoride and hexafluoropropylene.

25. The method of claim 18 wherein each of the substrates is a film or non-woven web made from material selected from the group consisting of paper, polyester, polypropylene, and polyethylene.