Lithium secondary battery

• US 20060068290A1
• Filed: 09/22/2005
• Published: 03/30/2006
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Panasonic Energy Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Minami, Hiroshi, Fukui, Atsushi, Yanagida, Toshio, Kamino, Maruo, Sunano, Taizou, Sunagawa, Takuya, Sawa, Shouichirou
• Granted Patent: US 7,682,744 B2
• Time in Patent Office: Days
• US Class Current: 429/231.100
• CPC Class Codes: C01G 45/1228 of the type [MnO2]n- , e.g. LiMnO2, Li[MxMn1-x]O2
• CPC Class Codes: C01G 51/42 containing alkali metals, e.g. LiCoO2
• CPC Class Codes: C01G 51/50 of the type [MnO2]n- , e.g. Li(CoxMn1-x)O2, Li(MyCoxMn1-x-y)O2
• CPC Class Codes: C01G 53/42 containing alkali metals, e.g. LiNiO2
• CPC Class Codes: C01G 53/50 of the type [MnO2]n- , e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/54 one element only
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• 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 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A lithium secondary battery having high capacity and good charge-discharge cycle performance is provided. The lithium secondary battery includes a negative electrode (2) containing silicon as a negative electrode active material, a positive electrode (1) containing a positive electrode active material, and a non-aqueous electrolyte. The positive electrode active material is a lithium-transition metal composite oxide including a layered structure represented by the chemical formula Li_aNi_xMn_yCO_zO₂, where a, x, y, and z satisfy the expressions: 0≦a≦1.3, x+y+z=1, 0<x, 0≦y≦0.5, and 0≦z.), and the theoretical electrical capacity ratio of the positive electrode to the negative electrode (positive electrode/negative electrode) is 1.2 or less.

Claims

1. A lithium secondary battery, comprising:

a negative electrode containing silicon as a negative electrode active material;

a positive electrode containing a positive electrode active material; and

a non-aqueous electrolyte, wherein

the positive electrode active material is a layered lithium-transition metal composite oxide represented by the chemical formula Li_aNi_xMn_yCo_zO₂, where a, x, y, and z satisfy the expressions 0≦

a≦

1.3, x+y+z=1, 0<

x, 0≦

y≦

0.5, and 0≦

z, and

a theoretical electrical capacity ratio of the positive electrode to the negative electrode (positive electrode/negative electrode) is 1.2 or less.

2. The lithium secondary battery according to claim 1, wherein x, y, and z in the chemical formula satisfy the expressions 0<

x≦

0.5, 0<

y≦

0.5, and 0≦

z.

3. The lithium secondary battery according to claim 1, wherein z in the chemical formula satisfies the expression 0<

z.

4. The lithium secondary battery according to claim 1, wherein the non-aqueous electrolyte contains carbon dioxide dissolved therein.

5. The lithium secondary battery according to claim 1, wherein the positive electrode active material contains 0.2 weight % or greater of lithium carbonate.

6. The lithium secondary battery according to claim 1, wherein the lithium-transition metal composite oxide has a BET specific surface area of 3 m²/g or less.

7. The lithium secondary battery according to claim 1, wherein the negative electrode includes a mixture layer containing a binder and active material particles containing silicon and/or silicon alloy, and a current collector made of a conductive metal foil, the mixture layer being disposed on the current collector.

8. The lithium secondary battery according to claim 7, wherein the mixture layer is sintered and disposed on a surface of the current collector.

9. A lithium secondary battery, comprising:

a negative electrode containing silicon as a negative electrode active material;

a positive electrode containing a positive electrode active material; and

a non-aqueous electrolyte, wherein

the positive electrode active material is a layered lithium-transition metal composite oxide represented by the chemical formula Li_aNi_xMn_yCo_zO₂, where a, x, y, and z satisfy the expressions 0≦

a≦

1.3, x+y+z=1, 0<

x≦

0.5, 0≦

y≦

0.5, and 0<

z, and

a theoretical electrical capacity ratio of the positive electrode to the negative electrode (positive electrode/negative electrode) is 1.2 or less.

10. The lithium secondary battery according to claim 9, wherein the positive electrode active material contains 0.2 weight % or greater of lithium carbonate.

11. The lithium secondary battery according to claim 9, wherein the lithium-transition metal composite oxide has a BET specific surface area of 3 m²/g or less.

12. The lithium secondary battery according to claim 9, wherein the negative electrode includes a mixture layer containing a binder and active material particles containing silicon and/or silicon alloy, and a current collector made of a conductive metal foil, the mixture layer being disposed on the current collector.

13. The lithium secondary battery according to claim 12, wherein the mixture layer is sintered and disposed on a surface of the current collector.

14. A lithium secondary battery, comprising:

a negative electrode containing silicon as a negative electrode active material;

a positive electrode containing a positive electrode active material; and

a non-aqueous electrolyte, wherein

the positive electrode active material is a layered lithium-transition metal composite oxide represented by the chemical formula Li_aNi_xMn_yCo_zO₂, where a, x, y, and z satisfy the expressions 0≦

a≦

1.3, x+y+z=1, 0<

x≦

0.5, 0≦

y≦

0.5, and 0<

z,

a theoretical electrical capacity ratio of the positive electrode to the negative electrode (positive electrode/negative electrode) is 1.2 or less, and

the non-aqueous electrolyte contains carbon dioxide dissolved therein.

15. The lithium secondary battery according to claim 14, wherein the positive electrode active material contains 0.2 weight % or greater of lithium carbonate.

16. The lithium secondary battery according to claim 14, wherein the lithium-transition metal composite oxide has a BET specific surface area of 3 m²/g or less.

17. The lithium secondary battery according to claim 14, wherein the negative electrode includes a mixture layer containing a binder and active material particles containing silicon and/or silicon alloy, and a current collector made of a conductive metal foil, the mixture layer being disposed on the current collector.

18. The lithium secondary battery according to claim 17, wherein the mixture layer is sintered and disposed on a surface of the current collector.