Mixed metal olivine electrode materials for lithium ion batteries

• US 8,541,136 B2
• Filed: 01/21/2009
• Issued: 09/24/2013
• Est. Priority Date: 01/17/2008
• Status: Active Grant

• Current Assignee: A123 Systems Incorporated
• Original Assignee: A123 Systems Incorporated
• Inventors: Pullen, Anthony E., Xu, Chuanjing, Wang, Liya, Beck, Larry, Sholtes, Phillip
• Primary Examiner(s): VANOY, TIMOTHY C
• Application Number:
  US12/357,008
• Publication Number:
  US 20090186277A1
• Time in Patent Office: 1,707 Days
• Field of Search: 429/221, 429/182.1, 429/223, 429/224, 429/231.5, 429/231.8, 429/231.95
• US Class Current: 429/221
• 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 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A positive electrode material is provided including an electroactive material having one or more phases comprising lithium (Li), an electroactive metal (M), and phosphate (PO₄), wherein in the fully lithiated state, the overall composition has a ratio of Li:M ranging from greater than about 1.0 to about 1.3, a ratio of (PO₄):M ranging from about 1.0 to about 1.132, M is one or more metals selected from the group consisting of Cr, Mn, Fe, Co, and Ni, and at least one phase includes an olivine lithium electroactive metal phosphate. In some instances, a composite cathode material including an electroactive olivine transition metal phosphate and a lithium and phosphate rich secondary phase is disclosed for use in a lithium ion battery.

Claims

1. A positive electrode material having an improved charge capacity at high discharge rates, the positive electrode material comprising:

an electroactive material having two or more phases comprising lithium (Li), an electroactive metal (M), and phosphate (PO₄),

wherein the overall composition of the electroactive material has a ratio of Li;

M ranging from greater than 1.1 to about 1.3, a ratio of (PO₄);

M ranging from about 1.0 to about 1.14,

the ratios Li;

M and (PO₄);

M are as compared to a stoichiometric composition for an olivine lithium transition metal phosphate (LiMPO₄),

M is one or more metals selected from the group consisting of Cr, Mn, Fe, Co, and Ni, and wherein the electroactive material comprises an olivine lithium electroactive metal phosphate phase and less than 10 wt % of a lithium-rich secondary phase or a lithium-rich and phosphate-rich secondary phase.

2. The positive electrode material of claim 1, wherein the electroactive material further comprises one or more dopant metals (Z) selected from the group consisting of V, Nb, Ti, AI, Mg, Mn, Co, Ni, and Zr, wherein M and Z are different.

3. The positive electrode material of claim 2, wherein

M comprises Fe,

the ratio of Li:

M ranges from greater than 1.1 to about 1.15,

the ratio of (PO₄);

M ranges from about 1.0 to about 1.03, and

the electroactive material comprises up to 5 mol % of the one or more dopant metals.

4. The positive electrode material of claim 2, wherein

M comprises Fe,

the ratio of Li:

M ranges from greater than 1.1 to about 1.15,

the ratio of (PO₄);

M ranges from about 1.03 to about 1.05, and

the electroactive material comprises up to 5 mol % of the one or more dopant metals.

5. The positive electrode material of claim 2, wherein

M comprises Fe,

the ratio of Li:

M ranges from greater than 1.1 to about 1.2,

the ratio of (PO₄);

M ranges from about 1.05 to about 1.07, and

the electroactive material comprises up to 5 mol % of the one or more dopant metals.

6. The positive electrode material of claim 2, wherein

M comprises Fe,

the ratio of Li:

M ranges from greater than 1.1 to about 1.3,

the ratio of (PO₄);

M ranges from about 1.07 to about 1.14, and

the electroactive material comprises up to 5 mol % of the one or more dopant metals.

7. The positive electrode material of claim 2, wherein the one or more dopant metals substitutes one or more of the lithium or electroactive metals in the olivine lithium electroactive metal phosphate.

8. The positive electrode material of claim 2, wherein the olivine lithium electroactive metal phosphate has the formula (Li₁₋

x,Z_x)MPO₄, x ranges from about 0.001 to about 0.05, and the ratio of (Li<sub>1−

x</sub>,Z_x);

M in the overall composition of the electroactive material ranges from greater than 1.1 to about 1.3.

9. The positive electrode material of claim 1, wherein the electroactive material comprises the olivine lithium electroactive metal phosphate phase and lithium-rich and phosphate rich secondary phase.

10. The positive electrode material of claim 9, wherein the secondary phase comprises lithium phosphate or lithium pyrophosphate.

21. A positive electrode comprising the positive electrode material of claim 1.

22. The positive electrode of claim 21, wherein the electroactive material further comprises one or more dopant metals (Z) selected from the group consisting of V, Nb, Ti, AI, Mg, Mn, Co, Ni, and Zr, wherein M and Z are different.

23. The positive electrode of claim 22, wherein the electroactive material comprises up to about 5 mol % of the one or more dopant metals.

24. The positive electrode of claim 22, wherein the one or more dopant metals substitutes one or more of the lithium or electroactive metals in the olivine lithium electroactive metal phosphate.

25. The positive electrode of claim 22, wherein the olivine lithium electroactive metal phosphate has the formula (Li₁₋

xZ_x)MPO₄, x ranges from about 0.001 to about 0.05, and the ratio of (Li<sub>1−

x</sub>Z_x);

M in the overall electroactive material ranges from greater than 1.1 to about 1.3.

26. The positive electrode of claim 21, wherein the electroactive material comprises the olivine lithium electroactive metal phosphate phase and lithium-rich and phosphate rich secondary phase.

27. The positive electrode of claim 21, further comprising a binder and an electronically conductive material.

11. A lithium secondary cell, comprising:

a 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 positive electrode comprises an electroactive material having two or more phases comprising lithium (Li), an electroactive metal (M), and phosphate (PO₄), wherein the overall composition in the electroactive material has a ratio of Li;

M ranging from greater than 1.1 to about 1.3, a ratio of (PO₄);

M ranging from about 1.0 to about 1.14, the ratios Li;

M and (PO₄);

M are as compared to a stoichiometric composition for an olivine lithium transition metal phosphate (LiMPO₄), M is one or more metals selected from the group consisting of Cr, Mn, Fe, Co, and Ni, and wherein the electroactive material comprises an olivine lithium electroactive metal phosphate phase and less than 10 wt % of a lithium-rich secondary phase or a lithium-rich and phosphate-rich secondary phase.

12. The lithium secondary cell of claim 11, wherein the electroactive material further comprises one or more dopant metals (Z) selected from the group consisting of V, Nb, Ti, AI, Mg, Mn, Co, Ni, and Zr, wherein M and Z are different.

13. The lithium secondary cell of claim 12, wherein the electroactive material comprises up to about 5 mol % of the one or more dopant metals.

14. The lithium secondary cell of claim 12, wherein the one or more dopant metals substitutes one or more of the lithium or electroactive metals in the olivine lithium electroactive metal phosphate.

15. The lithium secondary cell of claim 12, wherein the olivine lithium electroactive metal phosphate has the formula (Li₁₋

xZ_x)MPO₄, x ranges from about 0.001 to about 0.05, and the ratio of (Li<sub>1−

x</sub>Z_x);

M in the overall electroactive material ranges from greater than 1.1 to about 1.3.

16. The lithium secondary cell of claim 11, wherein the electroactive material comprises the olivine lithium electroactive metal phosphate phase and lithium-rich and phosphate rich secondary phase.

17. The lithium secondary cell of claim 11, wherein the negative electrode comprises a lithium intercalation compound or a lithium metal alloy.

18. The lithium secondary cell of claim 11, the negative electrode comprises carbon.

19. The lithium secondary cell of claim 18, wherein the negative electrode comprises graphitic carbon.

20. The lithium secondary cell of claim 18, wherein the carbon is selected from the group consisting of graphite, spheroidal graphite, mesocarbon microbeads and carbon fibers.