Method of making a cell using a lithium-deactivated carbon anode

• US 5,743,921 A
• Filed: 11/29/1996
• Issued: 04/28/1998
• Est. Priority Date: 07/03/1995
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Howie, Blake James, Nazri, Gholam-Abbas
• Primary Examiner(s): Maples, John S.
• Application Number:
  US08/785,976
• Time in Patent Office: 515 Days
• Field of Search: 29/623.5, 429/194
• US Class Current: 29/623.5
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/058 Construction or manufacture
• CPC Class Codes: H01M 10/38 Construction or manufacture
• CPC Class Codes: H01M 10/446 Initial charging measures
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/1393 of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/405 Alloys based on lithium
• 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 29/49115 including coating or impregnating

Abstract

A method of making a secondary, cathode-loaded, lithium-ion cell having a carbon anode including the principal step of cathodizing the carbon in a non-aqueous lithium-ion-conducting solution to deactivate the carbon by neutralizing or passivating any active sites therein.

Claims

1. In the method of assembling a secondary, lithium-ion cell in the substantially discharged state including the principle step of positioning an anode and a lithiated cathode opposite each other with a non-aqueous, lithium-ion-conducting, immobilized electrolyte therebetween, wherein said anode comprises lithium-intercalatable carbon and said lithiated cathode comprises a lithium-retentive material substantially saturated with a quantity of electrochemically reversible lithium species, the improvement comprising;

before said positioning, (a) initially cathodizing said carbon opposite a counterelectrode in a non-aqueous, lithium-ion-conducting solution so as to substantially saturate said carbon with said solution and electrolytically deposit enough lithium from said solution into said carbon to deactivate any active sites in said carbon yet leave said carbon with sufficient residual lithium capacity to reversibly intercalate said quantity of reversible lithium species, and (b) subsequently cathodizing said carbon in a non-aqueous, lithium-ion-conducting solution following said deactivation to intercalate a sufficient amount of lithium into said carbon to substantially compensate for any first cycle inefficiencies inherent in said lithium-retentive cathode material; and

effecting said positioning while said carbon is still saturated with said electrolyte;

whereby assembly of a near-stoichiometrically balanced battery is made possible.

2. The method according to claim 1 wherein said solution and said electrolyte have substantially the same composition.

3. The method according to claim 1 wherein said cathodizing is effected at substantially constant current, the voltage between said anode and said counterelectrode is monitored, and said initial cathodizing continues until said voltage falls below the electrolytic decomposition potential of said solution, and said subsequent cathodizing is effected at a voltage below said decomposition potential.

4. The method according to claim 3 wherein said cathodizing is effected at a cathode current density of at least about 2.5 amps/cm².

5. The method according to claim 1 wherein said cathode material comprises a transition metal chalcogenide.

6. The method according to claim 1 wherein said initial cathodizing is effected at a substantially constant voltage, the current between the carbon and the counterelectrode is monitored, and said cathodizing continues until said current falls to about zero.

7. The method according to claim 6 wherein the initial cathodizing voltage is below the electrolytic decomposition potential of said solution.

8. The method according to claim 1 wherein said counterelectrode comprises lithium.

9. The method according to claim 5 wherein said transition metal chalcogenide is an oxide.

10. The method according to claim 1 wherein said electrolyte is substantially immobilized in a polymer matrix.

11. The method according to claim 7 wherein said solution comprises propylene carbonate and said voltage is less than about 0.6 volts.

12. The method according to claim 9 wherein said transition metal comprises manganese.

13. The method according to claim 10 wherein said cathode material comprises a transition metal oxide.

14. The method according to claim 13 wherein said transition metal is manganese.

15. The method according to claim 1 wherein said subsequent cathodizing is sufficient to intercalate said carbon with up to about ten percent, by weight, of the lithium capacity of the cathode material.