Method of preparing electrochemical cells

• US 5,670,273 A
• Filed: 02/22/1996
• Issued: 09/23/1997
• Est. Priority Date: 02/22/1996
• Status: Expired due to Term

• Current Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Original Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Inventors: Velasquez, David A., Goglin, E. Lawrence, Holmes, Douglas B.
• Primary Examiner(s): Willis, Jr., Prince
• Assistant Examiner(s): KRUEGAR, JONATHAN
• Application Number:
  US08/603,894
• Time in Patent Office: 579 Days
• Field of Search: 429/162, 429/152, 29/623.3, 29/623.4, 29/623.1
• US Class Current: 429/162
• 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 10/0565 Polymeric materials, e.g. gel-type or solid-type
• 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: H01M 6/42 Grouping of primary cells into batteries H01M6/40 takes precedence
• 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

A method of fabricating electrochemical cells and batteries wherein the successive anode and cathode layers are separated by a polymeric electrolyte layer having a protruding polymer edge around its perimeter which reduces the likelihood of inadvertent contact between the anode and cathode current collectors is provided. The polymer edge functions as a non-conducting physical barrier positioned between adjacent current collectors.

Claims

1. A method of preparing an electrochemical cell comprising the steps of:

(a) forming an anode film onto at least one surface of an anode current collector to form an anode;

(b) forming a cathode film onto at least one surface of a cathode current collector to form a cathode; and

(c) interposing a polymeric layer containing an electrolyte solution between the anode and cathode wherein the polymeric electrolyte layer has a surface area that is larger than that of the anode film and cathode film wherein the perimeter of the polymeric electrolyte layer forms an exposed strip that serves as a barrier to direct contact between the anode current collector and cathode current collector provided that either (i) in forming the anode an anode film is formed on both surfaces of the anode current collector, or (ii) in forming the cathode a cathode film is formed on both surfaces of the cathode current collector, or (iii) in forming the anode, an anode film is formed on both surfaces of the anode current collector and in forming the cathode a cathode film is formed on both surfaces of the cathode current collector.

2. The method of claim 1 wherein said anode current collector has an anode film on each side and said cathode current collector has a cathode film on each side.

3. The method of claim 1 wherein said anode current collector has a perimeter that is substantially flush with the perimeter of the anode film and the cathode current collector has a perimeter that is substantially flush with the perimeter of the cathode film.

4. The method of claim 3 wherein said anode comprises an anode tab which is integral with said anode current collector and wherein said cathode comprises a cathode tab which is integral with said cathode current collector.

5. A method of preparing an electrochemical cell comprising the steps of:

(a) preparing a polymeric layer comprising a first plasticizer;

(b) covering at least one surface of an anode current collector with a layer of anode material comprising a first polymer, an intercalation carbon material, and a second plasticizer to form an anode precursor wherein each layer of said anode material has a surface area that is smaller than that of the polymeric layer;

(c) covering at least one surface of a cathode current collector with a layer of cathode material comprising a second polymer, a cathode active material, and a third plasticizer to form a cathode precursor wherein each layer of said cathode material has a surface area that is smaller than that of the polymeric layer;

(d) interposing the polymeric layer between the anode precursor and the cathode precursor so that the perimeter of the polymeric layer forms an exposed strip that serves as a barrier to direct contact between the anode current collector and cathode current collector;

(e) removing said first, second, and third plasticizers; and

(f) placing an electrolyte solution comprising an electrolyte solvent and an inorganic salt into said anode precursor, cathode precursor, and polymeric layer provided that either (i) in forming the anode precursor a layer of anode material covers both surfaces of the anode current collector or ii in forming the cathode precursor a layer of cathode material covers both surfaces of the cathode current collector, or (iii) in forming the anode precursor a layer of anode material covers both surfaces of the anode current collector and in forming the cathode precursor a layer of cathode material covers both surfaces of the cathode current collector.

6. The method of claim 5 wherein the anode material, cathode material, and polymeric layer each further comprises an inert liquid solvent and said method further comprises the step of removing said inert liquid solvents before step (f).

7. The method of claim 5 wherein the first, second, and third plasticizers comprise dibutyl phthalate.

8. The method of claim 6 wherein the inert liquid solvent comprises acetone.

9. The method of claim 5 wherein said anode current collector has an anode film on each side and said cathode current collector has a cathode film on each side.

10. The method of claim 5 wherein said anode current collector has a perimeter that is substantially flush with the perimeter of the anode film and the cathode current collector has a perimeter that is substantially flushed with the perimeter of the cathode film.

11. The method of claim 10 wherein said anode comprises an anode tab which is integral with said anode current collector and wherein said cathode comprises a cathode tab which is integral with said cathode current collector.

12. An electrochemical cell comprising:

an anode layer having an anode current collector with an anode film on at least one side of the anode current collector;

a cathode layer having a cathode current collector with a cathode film on at least one side of the cathode current collector; and

a polymeric layer containing an electrolyte solution comprising an electrolyte solvent and a salt that is interposed between the anode and cathode, wherein the polymeric layer has a surface area that is larger than that of the anode film and cathode film, wherein the perimeter of polymeric electrolyte layer forms an exposed strip that serves as a barrier to direct contact between the anode current collector and cathode current collector provided that either (i) both sides of the anode current collector are coated with an anode film, or (ii) both side of the cathode current collector are coated with a cathode film, or (iii) both sides of the anode current collector are coated with an anode film and both side of the cathode current collector are coated with a cathode film.

13. The electrochemical cell of claim 12 wherein said anode current collector has an anode film on each side and said cathode current collector has a cathode film on each side.

14. The electrochemical cell of claim 12 wherein said anode current collector has a perimeter that is substantially flush with the perimeter of the anode film and the cathode current collector has a perimeter that is substantially flush with the perimeter of the cathode film.

15. The electrochemical cell of claim 14 wherein said anode comprises an anode tab which is integral with said anode current collector and wherein said cathode comprises a cathode tab which is integral with said cathode current collector.

16. The electrochemical cell of claim 12, wherein the anode current collector comprises copper.

17. The electrochemical cell of claim 12, wherein the cathode current collector comprises aluminum.

18. The electrochemical cell of claim 12, wherein the anode film comprises carbon materials selected from the group consisting of graphite, cokes, and mesocarbons.

19. The electrochemical cell of claim 12, wherein the cathode film comprises cathodic material selected from the group consisting of lithiated cobalt oxides, lithiated manganese oxides, lithiated nickel oxides, and mixtures thereof.

20. The electrochemical cell of claim 18, wherein the cathode film comprises cathodic material selected from the group consisting of lithiated cobalt oxides, lithiated manganese oxides, lithiated nickel oxides, and mixtures thereof.