Redox shuttle for overdischarge protection in rechargeable lithium-ion batteries

• US 20050221168A1
• Filed: 03/31/2005
• Published: 10/06/2005
• Est. Priority Date: 04/01/2004
• Status: Active Grant

• Current Assignee: Chen Jun, Jeffrey R. Dahn
• Original Assignee: Chen Jun, Jeffrey R. Dahn
• Inventors: Chen, Jun, Dahn, Jeffrey R.
• Granted Patent: US 7,648,801 B2
• Time in Patent Office: Days
• US Class Current: 429/105
• 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 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/4235 Safety or regulating additives or arrangements in electrodes, separators or electrolyte H01M10/4242 takes precedence
• CPC Class Codes: H01M 10/446 Initial charging measures
• 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 2010/4292 Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/136 Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• CPC Class Codes: H01M 4/1391 of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery of series-connected rechargeable lithium ion cells each of which contains a negative electrode; a negative electrode current collector; a positive electrode; a positive electrode current collector; and an electrolyte comprising charge carrying medium, lithium salt and cyclable redox chemical shuttle. The negative electrode has a larger irreversible first cycle capacity loss than that of the positive electrode, and is driven to a potential above that of the positive electrode if the cell is discharged to a state of cell reversal. The shuttle has an electrochemical potential above the positive electrode maximum normal operating potential, and prevents the negative electrode potential from reaching even higher and more destructive positive values during overdischarge. The current collector has a lithium alloying potential below the negative electrode minimum normal operating potential. The battery chemically limits or eliminates cell damage due to repeated overdischarge, and may operate without electronic overdischarge protection circuitry.

Claims

1. A battery comprising a plurality of series-connected rechargeable lithium ion cells each comprising a negative electrode;

a negative electrode current collector;

a positive electrode;

a positive electrode current collector; and

an electrolyte comprising charge carrying medium, lithium salt and cyclable redox chemical shuttle, wherein the negative electrode has a larger irreversible first cycle capacity loss than that of the positive electrode, the redox chemical shuttle has an electrochemical potential above the positive electrode maximum normal operating potential, and the negative current collector has a lithium alloying potential below the negative electrode minimum normal operating potential.

2. A battery according to claim 1 wherein the plurality of cells can be discharged to 0 volts and recharged a plurality of times without substantially irreversibly reducing the recharge capacity of any cell.

3. A battery according to claim 1 comprising at least one weak cell having lower recharge capacity than at least one other cell, and wherein when the plurality of cells is discharged to 0 volts, the weak cell negative electrode potential increases to but does not exceed the shuttle oxidation potential.

4. A battery according to claim 1 wherein the redox chemical shuttle can provide the battery with overdischarge protection after at least 5 charge-discharge cycles at a charging voltage sufficient to oxidize the shuttle to its radical cation and an overcharge charge flow equivalent to 100% of the battery capacity during each cycle, and at a discharge to a battery potential of zero volts during each cycle.

5. A battery according to claim 1 wherein the redox chemical shuttle can provide the battery with overdischarge protection after at least 100 charge-discharge cycles at a charging voltage sufficient to oxidize the shuttle to its radical cation and an overcharge charge flow equivalent to 100% of the battery capacity during each cycle, and at a discharge to a battery potential of zero volts during each cycle.

6. A battery according to claim 1 wherein the negative electrode has a larger capacity than the positive electrode and the redox chemical shuttle can provide the battery with overcharge protection after at least 100 charge-discharge cycles at a charging voltage sufficient to oxidize the shuttle to its radical cation and an overcharge charge flow equivalent to 100% of the battery capacity during each cycle.

7. A battery according to claim 1 wherein the negative electrode comprises Li_4/3Ti_5/3O₄ or graphite.

8. A battery according to claim 1 wherein the negative electrode current collector has a dissolution potential above the shuttle reduction potential.

9. A battery according to claim 1 wherein the negative electrode current collector comprises aluminum.

10. A battery according to claim 1 wherein the negative electrode current collector and positive electrode current collector are made of the same material.

11. A battery according to claim 1 wherein the positive electrode comprises LiFePO₄.

12. A battery according to claim 1 wherein the negative electrode comprises Li_4/3Ti_5/3O₄, the negative electrode current collector comprises aluminum and the positive electrode comprises LiFePO₄.

13. A battery according to claim 1 wherein the charge carrying medium comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dimethoxyethane or combination thereof, and the lithium salt comprises LiPF₆, lithium bis(oxalato)borate or combination thereof.

14. A battery according to claim 1 wherein the redox chemical shuttle comprises an aromatic compound substituted with at least one tertiary carbon organic group and at least one alkoxy group.

15. A battery according to claim 1 wherein the redox chemical shuttle comprises 2,5-di-tert-butyl-1,4-dimethoxybenzene.

16. A battery according to claim 1 wherein the redox chemical shuttle has an electrochemical potential from about 3.7 to about 4.2 V vs. Li/Li⁺.

17. A battery according to claim 1 in the form of a replaceable battery pack without electronic overdischarge or electronic overcharge protection circuitry.

18. An electrical device comprising a) an electrical load and b) a battery comprising a plurality of series-connected rechargeable lithium ion cells each comprising a negative electrode;

a negative electrode current collector;

a positive electrode;

a positive electrode current collector; and

an electrolyte comprising charge carrying medium, lithium salt and cyclable redox chemical shuttle, wherein the negative electrode has a larger irreversible first cycle capacity loss than that of the positive electrode, the redox chemical shuttle has an electrochemical potential above the positive electrode maximum normal operating potential, and the negative current collector has a lithium alloying potential below the negative electrode minimum normal operating potential.

19. A device according to claim 18 wherein the load comprises a portable computer, tablet display, personal digital assistant or telephone.

20. A device according to claim 18 wherein the load comprises a motor, illumination source or heat source.

21. A device according to claim 18 wherein the negative electrode comprises Li_4/3Ti_5/3O₄, the negative electrode current collector comprises aluminum and the positive electrode comprises LiFePO₄.

22. A device according to claim 18 wherein the redox chemical shuttle comprises 2,5-di-tert-butyl-1,4-dimethoxybenzene.

23. A device according to claim 18 without electronic overdischarge protection circuitry.

24. A device according to claim 18 without electronic overcharge protection circuitry.