Composite compound with mixed crystalline structure

• US 8,057,711 B2
• Filed: 12/09/2008
• Issued: 11/15/2011
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: BYD Company Limited
• Original Assignee: BYD Company Limited
• Inventors: Tian, Ye, Xi, Xiaobing, Cheng, Tangli
• Primary Examiner(s): Nguyen; Khanh Tuan
• Application Number:
  US12/316,180
• Publication Number:
  US 20090220856A1
• Time in Patent Office: 1,071 Days
• Field of Search: 252/500, 252/182.1, 252/506, 252/510, 252/519.1, 252/519.15, 429/218.1, 429/224, 429/231.95, 429/232, 429/52, 429/220, 296/231
• US Class Current: 252/519.1
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 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: Y10T 29/49108 Electric battery cell making

Abstract

A composite lithium compound having a mixed crystalline structure is provided. Such compound can be formed by heating a lithium, iron, phosphorous and carbon mixed compound with another metal compound together. The resulting mixed metal crystal can exhibit superior electrical property and is a better cathode material for lithium secondary batteries.

Claims

1. A cathode active material comprising a mixed crystal, the mixed crystal having:

a first crystalline substance having one or more members with the general formulas Li_xM_y(XO₄)_z, LiMXO₅, LiMXO₆ and LiMX₂O₇, wherein;

0<

x/z≦

1 and 0≦

y/z≦

1;

M is selected from elements Na, Mn, Fe, Co, Ni, Ti, Nb and V;

X is selected from elements P, S, As, Mo and W; and

a second crystalline substance having one or more members with the general formula A_aM_bN_cO_d, wherein;

A, M and N are different metals selected from groups IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIIB, VIIB and VIII of the periodic table;

0≦

a≦

6, 0<

b≦

6, 0<

c≦

6 and 0<

d≦

12;

wherein a and b cannot both be 0 at the same time, wherein the first crystalline substance has a lattice, and at least a part of the second crystalline substance is received by and distributed in the lattice of the first crystalline structure, wherein the first crystalline substance and the second crystalline substance has molar ratios of about 1 to 0.01-0.05, and wherein the cathode active material has an electrical conductivity of about 0.01 to 10 S/cm at about 25°

C.

2. The material of claim 1, wherein the first crystalline substance includes one or more members selected from the group consisting of LiFePO₄, LiMnPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃, LiTi₂(PO₄)₃, Li₃V₂(PO₄)₃, Li₂NaV₂(PO₄)₃, LiTiPO₅, LiVMoO₆, LiVWO6, LiVP₂O₇ and LiFeAs₂O₇;

and wherein the second crystalline substance includes one or more members selected from the group consisting of Bi₄Ti₃O₁₂, CuNb₂O₆, MnTaO₄, FeWO₄, ZnZrNb₂O₈, NiNb₂O₆, NiZrNb₂O₈, FeTiNb₂O₈, MnTiNb₂O₈, MgSnNb₂O₈, ZnTa₂O₆, Cu_0.85Zn_0.15Nb₂O₆, YBa₃Ti₂O_8.5, Zr_0.75Ti_0.75Sn_0.5O₄, HfTiO₄ and MgNb₂O₆.

3. The material of claim 1, further comprising a carbon additive, wherein the carbon additive is capable of providing the mixed crystal with about 1-5% of carbon by weight.

4. The material of claim 3, wherein the carbon additive includes one or more members selected from the group consisting of carbon black, acetylene black, graphite, glucose, sucrose, citric acid, starch, dextrin and polyethylene glycol.

5. A lithium ion secondary battery comprising a battery case, electrodes and electrolyte, the electrodes and electrolyte being sealed within the battery case, the electrodes having wounded or stacked cathode, anode and divider film, the cathode further comprising the cathode material of claim 1.

6. A cathode active material comprising a mixed crystal, the mixed crystal having:

a first crystalline substance having a combination of lithium, iron and phosphorous sources, wherein the lithium, iron and phosphorous (Li;

Fe;

P) sources have molar ratios of about 0.95-1.1;

1;

0.95-1.1; and

a second crystalline substance having one or more members with the general formula A_aMbN_cO_d, wherein;

A, M and N are different metals selected from groups IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIIB, VIIB and VIII of the periodic table;

0≦

a≦

6, 0<

b≦

6, 0<

c≦

6 and 0<

d≦

12;

wherein a and b cannot both be 0 at the same time, wherein the first crystalline substance has a lattice, and at least a part of the second crystalline substance is received by and distributed in the lattice of the first crystalline structure, wherein the phosphorous source and the second crystalline substance has molar ratios of about 1 to 0.01-0.05, taking only the phosphorous source in the material into consideration, and wherein the cathode active material has an electrical conductivity of about 0.01 to 10 S/cm at about 25°

C.

7. The material of claim 6, wherein the second crystalline substance includes one or more members selected from the group consisting of Bi₄Ti₃O₁₂, CuNb₂O₆, MnTaO₄, FeWO₄, ZnZrNb₂O₈, NiNb₂O₆, NiZrNb₂O₈, FeTiNb₂O₈, MnTiNb₂O₈, MgSnNb₂O₈, ZnTa₂O₆, Cu_0.85Zn_0.15Nb₂O₆, YBa₃Ti₂O_8.5, Zr_0.75Ti_0.75Sn_0.5O₄, HfTiO₄ and MgNb₂O₆.

8. The material of claim 6, wherein the lithium source includes one or more members selected from the group consisting of lithium carbonate, lithium hydroxide, lithium oxalate and lithium acetate;

the iron source includes one or more members selected from the group consisting of ferrous oxalate, ferrous carbonate, iron acetate, iron oxide, iron phosphate, iron pyrophosphate and iron nitrate; and

the phosphate source includes one or more members selected from the group consisting of ammonium phosphate, ammonium dihydrogen phosphate, ammonium, iron phosphate, phosphoric acid and lithium dihydrogen phosphate.

9. The material of claim 6, further comprising a carbon additive, wherein the carbon additive is capable of providing the mixed crystal with about 1-5% of carbon by weight.

10. The material of claim 9, wherein the carbon additive includes one or more members selected from the group consisting of carbon black, acetylene black, graphite, glucose, sucrose, citric acid, starch, dextrin and polyethylene glycol.

11. A lithium ion secondary battery comprising a battery case, electrodes and electrolyte, the electrodes and electrolyte being sealed within the battery case, the electrodes having wounded or stacked cathode, anode and divider film, the cathode further comprising the cathode material of claim 6.

12. A cathode active material comprising a mixed crystal, the mixed crystal having:

a first crystalline substance having one or more members selected from the group consisting of LiFePO₄, LiMnPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃, LiTi₂(PO₄)₃, Li₃V₂(PO₄)₃, Li₂NaV₂(PO₄)₃, LiTiPO₅, LiVMoO₆, LiVWO6, LiVP₂O₇ and LiFeAs₂O₇; and

a second crystalline substance having one or more members selected from the group consisting of Bi₄Ti₃O₁₂, CuNb₂O₆, MnTaO₄, FeWO₄, ZnZrNb₂O₈, NiNb₂O₆, NiZrNb₂O₈, FeTiNb₂O₈, MnTiNb₂O₈, MgSnNb₂O₈, ZnTa₂O₆, Cu_0.85Zn_0.15Nb₂O₆, YBa₃Ti₂O_8.5, Zr_0.75Ti_0.75Sn_0.5O₄, HfTiO₄ and MgNb₂O₆, wherein the first crystalline substance has a lattice, and at least a part of the second crystalline substance is received by and distributed in the lattice of the first crystalline structure, wherein the first crystalline substance and the second crystalline substance has molar ratios of about 1 to 0.01-0.05, and wherein the cathode active material has an electrical conductivity of about 0.01 to 10 S/cm at about 25°

C.

13. The material of claim 12, further comprising a carbon additive, wherein the carbon additive is capable of providing the mixed crystal with about 1-5% of carbon by weight.

14. The material of claim 13, wherein the carbon additive includes one or more members selected from the group consisting of carbon black, acetylene black, graphite, glucose, sucrose, citric acid, starch, dextrin and polyethylene glycol.

15. A lithium ion secondary battery comprising a battery case, electrodes and electrolyte, the electrodes and electrolyte being sealed within the battery case, the electrodes having wounded or stacked cathode, anode and divider film, the cathode further comprising the cathode material of claim 12.