Multifunctional mixed metal olivines for lithium ion batteries

• US 8,187,735 B2
• Filed: 07/11/2008
• Issued: 05/29/2012
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: A123 Systems Incorporated
• Original Assignee: A123 Systems Incorporated
• Inventors: Chiang, Yet-Ming, Chu, Andrew C., Jang, Young-Il, Meethong, Nonglak, Riley, Gilbert N. Jr., Pullen, Anthony E., Thomas-Alyea, Karen E., Kao, Yu-Hua
• Primary Examiner(s): Maples, John S
• Application Number:
  US12/172,050
• Publication Number:
  US 20090123813A1
• Time in Patent Office: 1,418 Days
• Field of Search: None
• 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≦

1.2.

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. The method of claim 8, wherein the low voltage indicator comprises Li₇Ti₅O₁₂.