Electrode for a lithium battery

• US 6,203,944 B1
• Filed: 03/26/1998
• Issued: 03/20/2001
• Est. Priority Date: 03/26/1998
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Mao, Ou, McClure, Donald J., Krause, Larry J., Dahn, Jeffery R., Turner, Robert L., Buckett, Mary M.
• Primary Examiner(s): Chaney, Carol
• Assistant Examiner(s): TSANG FOSTER, SUSY N
• Application Number:
  US09/048,407
• Time in Patent Office: 1,090 Days
• Field of Search: 429/218.1, 429/231.95, 252/182.1, 420/557, 420/589, 420/560, 420/427, 420/429, 420/430, 420/425
• US Class Current: 429/218.1
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/446 Initial charging measures
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/387 Tin or alloys based on tin
• CPC Class Codes: H01M 4/40 Alloys based on alkali metals
• CPC Class Codes: H01M 4/623 fluorinated polymers
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An electrode for a lithium battery that includes (a) an electrochemically active metal element which, prior to cycling, is in the form of an intermetallic compound or an elemental metal and (b) a non-electrochemically active metal element. The electrode have high initial capacities that are retained even after repeated cycling. The electrode also exhibit high coulombic efficiencies.

Claims

1. An electrode for a lithium battery comprising a composition that includes (a) an electrochemically active metal element which, prior to cycling, is in the form of an intermetallic compound or an elemental metal and (b) a non-electrochemically active metal element,

wherein said composition has a microstructure characterized by one of (i) a single phase that includes said electrochemically active metal element and said non-electrochemically active metal element, (ii) a first phase that includes said electrochemically active metal element and a second, phase that includes said non-electrochemically active metal element in which said first and second phases share a common phase boundary, or (iii) a combination thereof,

wherein said composition, after said electrode has been cycled through one full charge-discharge cycle in the lithium battery, comprises crystalline regions having at least one dimension that is no greater than about 500 angstroms and that does not substantially increase after a total of at least 10 cycles.

2. An electrode according to claim 1 wherein said dimension does not substantially increase after a total of at least 100 cycles.

3. An electrode according to claim 1 wherein said dimension does not substantially increase after a total of at least 1000 cycles.

4. An electrode according to claim 1 wherein said dimension is no greater than about 100 angstroms.

5. An electrode according to claim 1 wherein said dimension is no greater than about 50 angstroms.

6. An electrode according to claim 1 wherein said composition comprises said crystalline regions prior to cycling.

7. An electrode according to claim 1 wherein said electrochemically active metal element is tin.

8. An electrode according to claim 1 wherein said non-electrochemically active metal element is selected from the group consisting of molybdenum, niobium, tungsten, tantalum, iron, copper, and combinations thereof.

9. An electrode according to claim 1 wherein said non-electrochemically active metal element is molybdenum.

10. An electrode according to claim 1 wherein said electrochemically active metal element is tin and said non-electrochemically active metal element is molybdenum.

11. An electrode according to claim 1 wherein said electrochemically active metal element is tin and said non-electrochemically active metal element is iron.

12. An electrode according to claim 1 wherein said electrochemically active metal element is tin and said non-electrochemically active metal element is niobium.

13. An electrode according to claim 1 wherein said electrochemically active metal element is tin and said non-electrochemically active metal element is tungsten.

14. An electrode according to claim 1 wherein said electrochemically active metal element is tin and said non-electrochemically active metal element is tantalum.

15. An electrode according to claim 1 wherein at least one of said crystalline regions comprises said electrochemically active metal element.

16. An electrode according to claim 1 wherein at least one of said crystalline regions comprises said non-electrochemically active metal element.

17. An electrode according to claim 1 wherein at least one of said crystalline regions comprises said electrochemically active metal element and at least another of said crystalline regions comprises said non-electrochemically active metal element.

18. An electrode according to claim 1 wherein said crystalline regions are separated by regions comprising said electrochemically active metal element and said non-electrochemically active metal element in which the relative proportions of said electrochemically active metal element and said non-electrochemically active metal element vary throughout the thickness direction of said composition.

19. An electrode according to claim 6 wherein, prior to cycling, said crystalline regions are separated by regions comprising said electrochemically active metal element and said non-electrochemically active metal element in which the relative proportions of said electrochemically active metal element and said non-electrochemically active metal element vary throughout the thickness direction of said composition.

20. An electrode according to claim 1 wherein said electrode, after being cycled to realize about 100 mAh/g of said composition in the lithium battery, exhibits a coulombic efficiency of at least about 99.0% after 100 full discharge cycles in the lithium battery.

21. An electrode according to claim 1 wherein said electrode, after being cycled to realize about 100 mAh/g of said composition in the lithium battery, exhibits a coulombic efficiency of at least about 99.8% after 100 full discharge cycles in the lithium battery.

22. An electrode according to claim 1 wherein said electrode, after being cycled to realize about 100 mAh/g of said composition in the lithium battery, exhibits a coulombic efficiency of at least about 99.9% after 100 full discharge cycles in the lithium battery.

23. An electrode composition according to claim 1 wherein said electrode is in the form of a thin film.

24. An electrode according to claim 1 wherein said electrode comprises a powder and a binder.

25. A lithium battery comprising:

(a) a first electrode comprising a composition that includes an electrochemically active metal element which, prior to cycling is in the form of an intermetallic compound or an elemental metal and a non-electrochemically active metal element,

wherein said composition has a microstructure characterized by one of (i) a single phase that includes said electrochemically active metal element and said non-electrochemically active metal element, (ii) a first phase that includes said electrochemically active metal element and a second phase that includes said non-electrochemically active metal element in which said first and second phases share a common phase boundary, or (iii) a combination thereof,

wherein said composition, after said battery has been cycled through one full charge-discharge cycle, comprises crystalline regions having at least one dimension that is no greater than about 500 angstroms and that does not substantially increase after a total of at least 10 cycles;

(b) a counterelectrode; and

(c) an electrolyte separating said electrode and said counterelectrode.