Lithium secondary cell with high charge and discharge rate capability

• US 20050233220A1
• Filed: 03/09/2005
• Published: 10/20/2005
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: A123 Systems Incorporated
• Original Assignee: A123 Systems Incorporated
• Inventors: Riley, Gilbert N. Jr., Chiang, Yet-Ming, Chu, Andrew C., Gozdz, Antoni S.
• Granted Patent: US 7,261,979 B2
• Time in Patent Office: Days
• US Class Current: 429/231.950
• 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 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2010/4292 Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• 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 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• 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

Abstract

A high capacity, high charge rate lithium secondary cell includes a high capacity lithium-containing positive electrode in electronic contact with a positive electrode current collector, said current collector in electrical connection with an external circuit, a high capacity negative electrode in electronic contact with a negative electrode current collector, said current collector in electrical connection with an external circuit, a separator positioned between and in ionic contact with the cathode and the anode, and an electrolyte in ionic contact with the positive and negative electrodes, wherein the total area specific impedance for the cell and the relative area specific impedances for the positive and negative electrodes are such that, during charging at greater than or equal to 4C, the negative electrode potential is above the potential of metallic lithium. The current capacity per unit area of the positive and negative electrodes each are at least 3 mA-h/cm², the total area specific impedance for the cell is less than about 20 Ω-cm², and the positive electrode has an area specific impedance r₁ and the negative electrode has an area specific impedance r₂, and wherein the ratio of r₁ to r₂ is at least about 10.

Claims

1. A high capacity, high charge rate lithium secondary cell, comprising:

a high capacity lithium-containing positive electrode in electronic contact with a positive electrode current collector, the current collector in electrical connection with an external circuit;

a high capacity negative electrode in electronic contact with a negative electrode current collector, said current collector in electrical connection with an external circuit;

a separator positioned between and in ionic contact with the cathode and the anode; and

an electrolyte in ionic contact with the positive and negative electrodes,

wherein the total area specific impedance for the cell and the relative area specific impedances for the positive and negative electrodes are such that, during charging at greater than or equal to 4C, the negative electrode potential is above the potential of metallic lithium.

3. The lithium secondary cell of claim 1, wherein the area specific impedance of the total cell is localized predominantly at the positive electrode.

4. The lithium secondary cell of claim 1, wherein the charge capacity per unit area of the positive and negative electrodes each are at least 0.75 mA-h/cm².

5. The lithium secondary cell of claim 1 or 2, wherein the current capacity per unit area of the positive and negative electrodes each are at least 1.0 mA-h/cm₂.

6. The lithium secondary cell of claim 1 or 2, wherein the charge capacity per unit area of the positive and negative electrodes each are at least 1.5 mA-h/cm².

7. The lithium secondary batter of claim 1, wherein the total area specific impedance for the cell is less than about 20 Ω

-cm², and wherein the positive electrode has an area specific impedance r₁ and the negative electrode has an area specific impedance r₂, and wherein the ratio of r₁ to r₂ is at least about 10.

8. The lithium secondary cell of claim 7, wherein the total area specific impedance for the cell is less than about 16 Ω

-cm² and wherein the ratio of r₁ to r₂ is at least about 7.

9. The lithium secondary cell of claim 7, wherein the total area specific impedance for the cell is less than about 14 Ω

-cm² and wherein the ratio of r₁ to r₂ is at least about 6.

10. The lithium secondary cell of claim 7, wherein the total area specific impedance for the cell is less than about 12 Ω

-cm² and wherein the ratio of r₁ to r₂ is at least about 5.

11. The lithium secondary cell of claim 7, wherein the total area specific impedance for the cell is less than about 10 Ω

-cm² and wherein the ratio of r₁ to r₂ is at least about 4.

12. The lithium secondary cell of claim 7, wherein the total area specific impedance for the cell is less than about 8 Ω

-cm and wherein the ratio of r₁ to r₂ is at least about 3.

13. The lithium secondary cell of claim 7, wherein the current capacity per unit area of the positive and negative electrodes each are at least 1.5 mA-h/cm².

22. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has a charge and discharge capacity measured at a C-rate of 10C that is greater than 90% of the nominal capacity measured at a C-rate of 1/10C.

23. The lithium secondary cell of claim 1 or 2, wherein the conductivity of the positive electrode does not increase more than a factor of 2 over the state of charge.

24. The lithium secondary cell of claim 1 or 2, wherein the conductivity of the positive electrode does not increase more than a factor of 5 over the state of charge.

25. The lithium secondary cell of claim 1 or 2, wherein an electroactive material of the positive electrode comprises a lithium transition metal phosphate.

26. The lithium secondary cell of claim 25, wherein the transition metal of the lithium transition metal phosphate comprises one or more of vanadium, chromium, manganese, iron, cobalt and nickel.

27. The lithium secondary cell of claim 25, wherein the lithium transition metal phosphate is of the formula (Li_1-xZ_x)MPO₄, where M is one or more of vanadium, chromium, manganese, iron, cobalt and nickel, and Z is one or more of titanium, zirconium, niobium, aluminum, or magnesium, and x ranges from about 0.005 to about 0.05.

28. The lithium secondary cell of claim 27, wherein Z is selected from the group consisting of zirconium and niobium.

29. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has a specific surface area of greater than about 10 m²/g.

30. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has a specific surface area of greater than about 15 m²/g.

31. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has a specific surface area of greater than about 20 m²/g.

32. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has a specific surface area of greater than about 30 m²/g.

33. The lithium secondary cell of claim 1 or 2, wherein the position electrode has pore volume in the range of about 40% to about 70% by volume.

34. The lithium secondary cell of claim 1 or 2, wherein the positive electrode has thickness in the range of about 50 μ

m to about 125 μ

m.

35. The lithium secondary cell of claim 1 or 2, wherein the negative electrode comprises carbon.

36. The lithium secondary cell of claim 35, wherein the negative electrode comprises graphitic carbon.

37. The lithium secondary cell of claim 35, wherein the carbon is selected from the group consisting of graphite, spheroidal graphite, mesocarbon microbeads and carbon fibers.

38. The lithium secondary cell of claim 35, wherein the carbon has an average particle size of less than about 25 μ

m.

39. The lithium secondary cell of claim 35, wherein the carbon has an average particle size of less than about 15 μ

m.

40. The lithium secondary cell of claim 35, wherein the carbon has an average particle size of less than about 10 μ

m.

41. The lithium secondary cell of claim 35, wherein the carbon has an average particle size of less than about 6 μ

m.

42. The lithium secondary cell of claim 35, wherein the negative electrode has pore volume in the range of about 20 and 40% by volume.

43. The lithium secondary cell of claim 35, wherein the negative electrode has thickness in the range of about 20 μ

m to about 75 μ

m.

44. The lithium secondary cell of claim 35, wherein the carbon has a fast diffusion direction parallel to the long dimension of the particle with a dimension less than 6*(diffusion coefficient of fast direction/diffusion coefficient of MCMB)^0.5 and a thickness less than about 75 microns and a porosity greater than 25%.

2. A high capacity, high charge rate lithium secondary cell, comprising:

a lithium-containing positive electrode in electronic contact with a positive electrode current collector, said current collector in electrical connection with an external circuit;

a negative electrode in electronic contact with a negative electrode current collector, said current collector in electrical connection with an external circuit;

a separator positioned between and in ionic contact with the cathode and the anode; and

an electrolyte in ionic contact with the positive and negative electrodes,

wherein the charge capacity per unit area of the positive and negative electrodes each are at least 0.75 mA-h/cm², and

wherein the total area specific impedance for the cell is less than about 20 Ω

-cm².

14. The lithium cell of claim 2, wherein the total area specific impedance for the cell is less than about 16 Ω

-cm².

15. The lithium cell of claim 2, wherein the total area specific impedance for the cell is less than about 14 Ω

-cm².

16. The lithium cell of claim 2, wherein the total area specific impedance for the cell is less than about 12 Ω

-cm².

17. The lithium cell of claim 2, wherein the total area specific impedance for the cell is less than about 10 Ω

-cm².

18. The lithium secondary cell of claim 2, wherein the negative electrode has an area specific impedance, r₂, of less than or equal to about 3.0 Ω

-cm².

19. The lithium secondary cell of claim 2, wherein the negative electrode has an area specific impedance, r₂, of less than or equal to about 2.5 Ω

-cm².

20. The lithium secondary cell of claim 2, wherein the negative electrode has an area specific impedance, r₂, of less than or equal to about 2.0 Ω

-cm².

21. The lithium secondary cell of claim 2, wherein the negative electrode has an area specific impedance, r₂, of less than or equal to about 1.5 Ω

-cm².

45. A method of charging a lithium secondary cell, comprising:

(a) providing a lithium secondary cell, comprising;

a high capacity lithium-containing positive electrode in electronic contact with a positive electrode current collector, said current collector in electrical connection with an external circuit;

a high capacity negative electrode in electronic contact with a negative electrode current collector, said current collector in electrical connection with an external circuit;

a separator positioned between and in ionic contact with the cathode and the anode; and

an electrolyte in ionic contact with the positive and negative electrodes,

wherein the total area specific impedance for the cell and the relative area specific impedances for the positive and negative electrodes are such that, during charging at greater than or equal to 4C, the negative electrode potential is above the potential of metallic lithium; and

(b) charging the cell at a C-rate of at least 4C, wherein at least 95% state of charge is obtained in less than 15 minutes.

46. The method of claim 45, comprising charging the cell at a C-rate of 10C, wherein at least 90% state of charge is obtained in less than 6 minutes.

47. The method of claim 45, comprising charging the cell at a C-rate of 20C, wherein at least 80% state of charge is obtained in less than 3 minutes.

48. The method of claim 45, wherein the cell is charged at an overpotential.

49. The method of claim 45, wherein the cell is charged at a potential near the oxidation potential of the electrolyte.

50. A low fade lithium secondary cell, comprising:

a lithium-containing positive electrode, said positive electrode in electronic contact with a positive electrode current collector, said current collector in electrical connection with an external circuit;

a negative electrode in electronic contact with a negative electrode current collector, said current collector in electrical connection with an external circuit;

a separator positioned between and in ionic contact with the cathode and the anode; and

an electrolyte in ionic contact with the positive and negative electrodes,

wherein the total area specific impedance for the cell and the relative area specific impedances for the positive and negative electrodes are such that the cell is capable of achieving at least about 80% state of charge within about 25 minutes, and

wherein the cell is capable of multiple charge/discharge cycles with a capacity loss of less than about 0.2% per cycle.

51. The cell of claim 50, wherein the cell is capable of achieving at least about 90% state of charge within about 12 minutes, and wherein the cell is capable of multiple charge/discharge cycles with a capacity loss of less than about 0.1% per cycle.

52. The cell of claim 50, wherein the cell is capable of achieving at least about 95% state of charge within about 6 minutes, and wherein the cell is capable of multiple charge/discharge cycles with a capacity loss of less than about 0.05% per cycle.