MULTIFUNCTIONAL MIXED METAL OLIVINES FOR LITHIUM ION BATTERIES

• US 20090123813A1
• Filed: 07/11/2008
• Published: 05/14/2009
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: A123 Systems Incorporated
• Original Assignee: A123 Systems Incorporated
• Inventors: JANG, Young-Il, KAO, Yu-Hua, MEETHONG, Nonglak, PULLEN, Anthony E., CHIANG, Yet-Ming, CHU, Andrew C., RILEY, Gilbert N. JR., THOMAS-ALYEA, Karen E.
• Granted Patent: US 8,187,735 B2
• Time in Patent Office: Days
• US Class Current: 429/50
• CPC Class Codes: C01B 25/45 containing plural metal, or metal and ammonium
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 4/364 as mixtures
• 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 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Electroactive compositions are disclosed for use in lithium ion battery electrodes. The compositions, such as multifunctional mixed metal olivines, provide an electrochemical cell having a plurality of open circuit voltages at different states of charge. The compositions afford improved state-of-charge monitoring, overcharge protection and/or overdischarge protection for lithium ion batteries.

Claims

1. A method for monitoring and maintaining the performance of an electrochemical cell, comprising:

providing an electrochemical cell having a positive electrode and negative electrode separated by an electrolyte, the composition of electroactive materials of the positive electrode, the negative electrode, or both selected to provide a cell having a plurality of open circuit voltages at different states of charge, said composition selected to provide a change in voltage of the cell at a pre-selected state of charge;

monitoring the cell to detect a change in cell voltage; and

changing a current or power into or out of the cell in response to the detected change in voltage.

2. The method of claim 1, wherein the positive electrode electroactive materials are selected to provide a cell having a plurality of open circuit voltages at different states of charge.

3. The method of claim 1, wherein the negative electrode electroactive materials are selected to provide a cell having a plurality of open circuit voltages at different states of charge.

4. The method of claim 1, wherein the positive electrode and negative electrode electroactive materials are selected to provide a cell having a plurality of open circuit voltages at different states of charge.

5. The method of claim 1, wherein the positive electrode electroactive material comprises a primary electroactive material and a high voltage indicator, said high voltage indicator having an equilibrium potential that results in a cell voltage that is close to but below a first pre-selected voltage threshold.

6. The method of claim 5, wherein the negative electrode electroactive material comprises a primary electroactive material and a low voltage indicator, said low voltage indicator having an equilibrium potential that results in a cell voltage that is close to but above a second pre-selected voltage threshold.

7. The method of claim 6, wherein the low voltage indicator is subjected to lithiation prior to being added to the electrode.

8. The method of claim 1, wherein the positive electrode electroactive material comprises a primary electroactive material and a low voltage indicator, said low voltage indicator having an equilibrium potential that results in a cell voltage that is close to but above a pre-selected voltage threshold.

9. The method of claim 8, wherein the low voltage indicator is subjected to lithiation prior to being added to the electrode.

10. The method of claim 8, wherein the primary electroactive material comprises a lithium metal phosphate and the low voltage indicator comprises a lithium metal oxide.

11. The method of claim 10, wherein the low voltage indicator comprises LiAl_xMn₁₋

xO₂ where 0≦

x<

0.05.

12. The method of claim 8, wherein the low voltage indicator comprises Li₂FeSiO₄.

13. The method of claim 8, wherein the primary electroactive material comprises a lithium metal phosphate and the low voltage indicator comprises lithium Ti, Mg or Zr phosphate.

14. The method of claim 1, wherein the positive electrode electroactive material comprises a primary electroactive material;

a high voltage indicator, said high voltage indicator having an equilibrium potential that results in a cell voltage that is close to but below an upper limiting voltage of the cell; and

a low voltage indicator, said low voltage indicator having an equilibrium potential that results in a cell voltage that is close to but above a lower limiting voltage of the cell.

15. The method of claim 14, wherein the low voltage indicator is subjected to lithiation prior to being added to the electrode.

16. The method of claim 1, wherein the negative electrode electroactive material comprises a primary electroactive material and a low voltage indicator, said low voltage indicator having an equilibrium potential that results in a cell voltage that is close to but above a lower limiting voltage of the cell.

17. The method of claim 16, wherein the low voltage indicator is subjected to lithiation prior to being added to the electrode.

18. The method of claim 1, wherein the positive electrode electroactive material comprises lithium metal phosphate.

19. The method of claim 1, wherein the positive electrode electroactive material comprises about 60-95 molar % of a first primary electroactive material, wherein the first primary electroactive material is a lithium metal phosphate;

about 0-50 molar % of a second primary electroactive material;

about 1-30 molar % of a high voltage indicator material having an open-circuit potential greater than each of the first and second primary electroactive materials; and

about 1-30 molar % of a low voltage indicator material having an open-circuit potential less than each of the first and second primary electroactive materials.

20. The method of claim 1, wherein the positive electrode electroactive material comprises an olivine lithium metal phosphate material having the formula Li_xM′

_yM″

_zM′

″

_wPO₄, wherein

M′

is one or more of Mn and Fe;

M″

is one or more of Mn, Co and Ni;

M′

″

is one or more of Ti, Zr and Mg;

M′

is not the same as M″

;

0≦

x≦

1.2;

0.5≦

y≦

0.95;

0.025≦

z≦

0.5;

0.025≦

w≦

0.25; and

0.8≦

y+z+w≦

1 0.2.

21. The method of claim 1, wherein monitoring the cell to detect a change in voltage comprises measuring the voltage or monitoring the first or second derivative of the voltage with respect to time or capacity.

22. The method of claim 21, wherein impedance compensation is employed in measuring the voltage.

23. The method of claim 1, wherein the current is changed by limiting the charge or discharge current into the cell.

24. The method of claim 1, wherein the current is changed by decreasing the rate of charge or discharge.

25. The method of claim 1, wherein the current is changed by terminating charge or discharge.

26. The method of claim 1, wherein the current is changed by switching from a charging state to a discharging state.

27. The method of claim 1, wherein the current is changed by switching from a discharging state to a charging state.

28. An electroactive composition for use as a positive electrode material in an electrochemical cell, comprising:

about 60-95 molar % of a first primary electroactive material, wherein the first primary electroactive material is a lithium metal phosphate;

about 0-50 molar % of a second primary electroactive material;

about 1-30 molar % of a high voltage indicator material having an open-circuit potential greater than each of the first and second primary electroactive materials; and

about 1-30 molar % of a low voltage indicator material having an open-circuit potential less than each of the first and second primary electroactive materials.

29. The electroactive composition of claim 28, comprising:

about 60-95 molar % of the first primary electroactive material;

about 0-20 molar % of the second primary electroactive material;

about 1-20 molar % of the high voltage indicator material; and

about 1-20 molar % of the low voltage indicator material.

30. The electroactive composition of claim 28, wherein the high voltage indicator material and the low voltage indicator material are initially present in a state of lithiation allowing delithiation at their respective higher and lower voltages in a cell.

31. The electroactive composition of claim 28, wherein the composition is a physical mixture and the high voltage indicator material and the low voltage indicator material are initially present in a state of lithiation allowing delithiation at their respective higher and lower voltages in a cell.

32. The electroactive composition of claim 28, wherein the composition is a single phase material.

33. The electroactive composition of claim 28, wherein the composition is a multi-phase material.

34. The electroactive composition of claim 28, wherein the low voltage indicator material is a lithium metal oxide.

35. The electroactive composition of claim 34, wherein the low voltage indicator material is LiAl_xMn₁₋

xO₂ where 0≦

x≦

0.05.

36. The electroactive composition of claim 28, wherein the low voltage indicator material is Li₂FeSiO₄.

37. The electroactive composition of claim 28, wherein the first primary electroactive material comprises lithium iron phosphate, the second primary electroactive material comprises a compound containing Mn, the high voltage indicator material comprises a compound containing one or more of Co and Ni, and the low voltage indicator material comprises a compound containing one or more of Ti, Zr and Mg.

38. The electroactive composition of claim 37, wherein the second primary electroactive material comprises lithium manganese phosphate, the high voltage indicator material comprises one or more of lithium Co and Ni phosphate, and the low voltage indicator material comprises one or more of lithium Ti, Zr and Mg phosphate.

39. An electroactive composition for use as a positive electrode material in an electrochemical cell, comprising an olivine lithium metal phosphate material having the formula Li_xM′

_yM″

_zM′

″

_wPO₄, wherein

M′

is one or more of Mn and Fe;

M″

is one or more of Mn, Co and Ni;

M′

″

is one or more of Ti, Zr and Mg;

M′

is not the same as M″

;

0≦

x≦

1.2;

0.5≦

y≦

0.95;

0.025≦

z≦

0.5;

0.025≦

w≦

0.25; and

0.8≦

y+z+w≦

1.2.

40. An electrochemical cell, comprising:

(a) a positive electrode comprising a positive electrode electroactive material including

about 60-95 molar % of a first primary electroactive material, wherein the first primary electroactive material is a lithium metal phosphate;

about 0-50 molar % of a second primary electroactive material;

about 1-30 molar % of a high voltage indicator material having an open-circuit potential greater than each of the first and second primary electroactive materials; and

about 1-30 molar % of a low voltage indicator material having an open-circuit potential less than each of the first and second primary electroactive materials; and

(b) a negative electrode separated from the positive electrode by an electrolyte.

41. The electrochemical cell of claim 40, further comprising a negative current collector in electrical communication with the negative electrode,

wherein the low voltage indicator material has an open circuit potential of less than the dissolution potential of the current collector.

42. The electrochemical cell of claim 40, wherein the high voltage indicator material and the low voltage indicator material are initially present in a state of lithiation allowing delithiation at their respective higher and lower voltages in the cell.

43. The electrochemical cell of claim 40, wherein the low voltage indicator material is a lithium metal oxide.

44. The electrochemical cell of claim 43, wherein the low voltage indicator material is LiAl_xMn₁₋

xO₂ where 0≦

x<

0.05.

45. The electrochemical cell of claim 40, wherein the low voltage indicator material is Li₂FeSiO₄.

46. The electrochemical cell of claim 40, wherein the first primary electroactive material comprises lithium iron phosphate, the second primary electroactive material comprises a compound containing Mn, the high voltage indicator material comprises a compound containing one or more of Co and Ni, and the low voltage indicator material comprises a compound containing one or more of Ti, Zr and Mg.

47. The electrochemical cell of claim 46, wherein the second primary electroactive material comprises lithium manganese phosphate, the high voltage indicator material comprises one or more of lithium Co and Ni phosphate, and the low voltage indicator material comprises one or more of lithium Ti, Zr and Mg phosphate.

48. An electrochemical cell, comprising:

(a) a positive electrode comprising a positive electrode electroactive material including an olivine lithium metal phosphate having the formula Li_xM′

_yM″

_zM′

″

_wPO₄, wherein

M′

is one or more of Mn and Fe;

M″

is one or more of Mn, Co and Ni;

M′

″

is one or more of Ti, Zr and Mg;

M′

is not the same as M″

;

0≦

x≦

1.2;

0.5≦

y≦

0.95;

0.025≦

z≦

0.5;

0.025≦

w≦

0.25; and

0.8≦

y+z+w≦

1.2; and

(b) a negative electrode separated from the positive electrode by an electrolyte.

49. An electrochemical cell, comprising:

a positive electrode comprising a positive electrode electroactive material;

a negative electrode separated from the positive electrode by an electrolyte; and

a negative current collector in electrical communication with the negative electrode,

wherein the negative electrode comprises a negative electrode electroactive material and an additive having an open circuit potential of less than the dissolution potential of the current collector.

50. The electrochemical cell of claim 49, wherein the additive provides about 1-20% of the lithium storage capacity of the positive electrode at a reduction-oxidation potential for lithium intercalation that is between 0.2 and 3.3V with respect to Li/Li⁺.

51. The electrochemical cell of claim 49, wherein the additive is Li₂FeSiO₄.

52. The electrochemical cell of claim 49, wherein the electrochemical cell is a rechargeable battery.

53. The electrochemical cell of claim 49, wherein the positive electrode electroactive material comprises lithium metal phosphate.

54. The electrochemical cell of claim 49, wherein the positive electrode electroactive material comprises lithium iron phosphate.

55. The electrochemical cell of claim 49, wherein the negative electrode electroactive material comprises carbon, graphite, alloy or titanate.

56. An electroactive composition for use as a positive electrode material in an electrochemical cell, comprising an olivine lithium metal phosphate material having the formula Li_xM′

_yM″

_zPO₄, wherein

M′

is one or more of Mn and Fe;

M″

is one or more of Mn, Co and Ni;

M′

is not the same as M″

;

0≦

x≦

1.2;

0.7≦

y≦

0.95;

0.02≦

z≦

0.3; and

0.8≦

y+z≦

1.2.

57. The composition of claim 56, wherein 0.02≦

z≦

0.1.

58. The composition of claim 57, wherein y+z=1.

59. The composition of claim 56, wherein M′

is Fe and 0.02≦

z≦

0.1.

60. The composition of claim 59, wherein y+z=1.

61. The composition of claim 56, wherein 0.8≦

y+z<

1.

62. The composition of claim 56, wherein 1<

y+z≦

1.2.

63. An electrochemical cell, comprising:

(a) a positive electrode comprising a positive electrode electroactive material including an olivine lithium metal phosphate having the formula Li_xM′

_yM″

_zPO₄, wherein

M′

is one or more of Mn and Fe;

M″

is one or more of Mn, Co and Ni;

M′

is not the same as M″

;

0≦

x≦

1.2;

0.7≦

y≦

0.95;

0.02≦

z≦

0.3; and

0.8≦

y+z≦

1.2; and

(b) a negative electrode separated from the positive electrode by an electrolyte.