Positive electrode for lithium secondary battery, and lithium secondary battery using the same

• US 20070015058A1
• Filed: 07/14/2006
• Published: 01/18/2007
• Est. Priority Date: 07/14/2005
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nishino, Hajime, Takezawa, Hideharu
• Granted Patent: US 7,803,485 B2
• Time in Patent Office: Days
• US Class Current: 429/231.950
• 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 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 2300/004 Three solvents
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/136 Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• 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 4/525 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: 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: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A positive electrode for use in a lithium secondary battery comprises a positive electrode current collector, and a positive electrode film which is carried on the positive electrode current collector and includes a plurality of mixture layers. The positive electrode film contains, as a positive electrode active material, two or more kinds of lithium-containing compounds having exothermic initiation temperatures different from each other. At least one kind of the two or more kinds of lithium-containing compounds has the exothermic initiation temperature of 300° C. or higher. A first mixture layer of the plural mixture layers closest to the positive electrode current collector contains at least one kind of the lithium-containing compound having the exothermic initiation temperature of 300° C. or higher.

Claims

1. A positive electrode, for use in a lithium secondary battery, comprising a positive electrode current collector, and a positive electrode film which is carried on the positive electrode current collector and includes a plurality of mixture layers, wherein

the positive electrode film contains, as a positive electrode active material, two or more kinds of lithium-containing compounds having exothermic initiation temperatures different from each other,

at least one kind of the two or more kinds of lithium-containing compounds has the exothermic initiation temperature of 300°

C. or higher, and

a first mixture layer of the plural mixture layers, closest to the positive electrode current collector, contains at least one kind of the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher.

2. The positive electrode according to claim 1, wherein,

in the first mixture layer, a content of the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is larger than a content of the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher.

3. The positive electrode according to claim 1, wherein

the positive electrode active material in the first mixture layer essentially consists of the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher.

4. The positive electrode according to claim 1, wherein

the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is one kind selected from the group consisting of lithium-manganese-based oxides, lithium-nickel-cobalt-manganese-based oxides, and olivine-type lithium-phosphate-based compounds.

5. The positive electrode according to claim 4, wherein

the lithium-manganese-based oxides include a lithium manganese oxide represented by LiMn₂O₄.

6. The positive electrode according to claim 4, wherein

the lithium-nickel-cobalt-manganese-based oxides include a lithium nickel manganese cobalt oxide represented by Li_aNi₁₋

(b+c)Mn_bCo_cO₂ where a, b, and c satisfy 1≦

a≦

1.2, 0.1≦

b≦

0.5, and 0.1≦

c≦

0.5.

7. The positive electrode according to claim 4, wherein

the olivine-type lithium-phosphate-based compounds include an olivine-type lithium phosphate compound represented by LiMePO₄ where Me is at least one element selected from the group consisting of Co, Ni, Fe, and Mn.

8. The positive electrode according to claim 1, wherein

the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is at least one kind selected from the group consisting of lithium-cobalt-based oxides and lithium-nickel-based oxides.

9. The positive electrode according to claim 8, wherein

the lithium-cobalt-based oxides include a lithium-cobalt-based oxide represented by LiCoO₂ or Li_aCo₁₋

(b+c)Mg_bM_cO₂ where a, b, and c satisfy 1≦

a≦

1.05, 0.005≦

b≦

0.10, and 0.005≦

c≦

0.10, and M is at least one element selected from the group consisting of Al, Sr, and Ca.

10. The positive electrode according to claim 8, wherein

the lithium-nickel-based oxides include a lithium-nickel-based oxide represented by Li_aNi₁₋

(b+c)Co_bM_cO₂ where a, b, and c satisfy 1≦

a≦

1.05, 0.1≦

b≦

0.35, and 0.005≦

c≦

0.30, and M is at least one element selected from the group consisting of Al, Sr, and Ca.

11. A lithium secondary battery comprising the positive electrode according to claim 1, a negative electrode, and a non-aqueous electrolyte.

12. A positive electrode, for use in a lithium secondary battery, comprising a positive electrode current collector, and a positive electrode film carried on the positive electrode current collector, wherein

the positive electrode film contains, as a positive electrode active material, two or more kinds of lithium-containing compounds having exothermic initiation temperatures different from each other,

at least one kind of the two or more kinds of lithium-containing compounds has the exothermic initiation temperature of 300°

C. or higher, and

a content of the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is increased in a thickness direction of the positive electrode film from an outermost layer of the positive electrode film toward the positive electrode current collector.

13. The positive electrode according to claim 12, wherein

a portion of the positive electrode film, closest to the positive electrode current collector, contains the positive electrode active material essentially consisting of the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher.

14. The positive electrode according to claim 12, wherein

the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is one kind selected from the group consisting of lithium-manganese-based oxides, lithium-nickel-cobalt-manganese-based oxides, and olivine-type lithium-phosphate-based compounds.

15. The positive electrode according to claim 14, wherein

the lithium-manganese-based oxides include a lithium manganese oxide represented by LiMn₂O₄.

16. The positive electrode according to claim 14, wherein

the lithium-nickel-cobalt-manganese-based oxides include a lithium nickel manganese cobalt oxide represented by Li_aNi₁₋

(b+c)Mn_bCo_cO₂ where a, b, and c satisfy 1≦

a≦

1.2, 0.1≦

b≦

0.5, and 0.1≦

c≦

0.5.

17. The positive electrode according to claim 14, wherein

the olivine-type lithium-phosphate-based compounds include an olivine-type lithium phosphate compound represented by LiMePO₄ where Me is at least one element selected from the group consisting of Co, Ni, Fe, and Mn.

18. The positive electrode according to claim 12, wherein

the lithium-containing compound other than the lithium-containing compound having the exothermic initiation temperature of 300°

C. or higher is at least one kind selected from the group consisting of lithium-cobalt-based oxides and lithium-nickel-based oxides.

19. The positive electrode according to claim 18, wherein

the lithium-cobalt-based oxides include a lithium-cobalt-based oxide represented by LiCoO₂ or Li_aCo₁₋

(b+c)Mg_bM_cO₂ where a, b, and c satisfy 1≦

a≦

1.05, 0.005≦

b≦

0.10, and 0.005≦

c≦

0.10, and M is at least one element selected from the group consisting of Al, Sr, and Ca.

20. The positive electrode according to claim 18, wherein

the lithium-nickel-based oxides include a lithium-nickel-based oxide represented by LiNi₁₋

(b+c)Co_bM_cO₂ where a, b, and c satisfy 1≦

a≦

1.05, 0.1≦

b≦

0.35, and 0.005≦

c≦

0.30, and M is at least one element selected from the group consisting of Al, Sr, and Ca.

21. A lithium secondary battery comprising the positive electrode according to claim 12, a negative electrode, and a non-aqueous electrolyte.