NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• US 20010016289A1
• Filed: 01/08/1998
• Published: 08/23/2001
• Est. Priority Date: 05/09/1996
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: NISHINO, HAJIME, KOSHINA, HIZURU, OURA, TAKAFUMI, KITAGAWA, MASAKI
• Granted Patent: US 6,713,217 B2
• Time in Patent Office: Days
• US Class Current: 429/249
• CPC Class Codes: H01M 10/05 Accumulators with non-aqueous electrolyte H01M10/39 takes precedence
• 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 10/0569 characterised by the solvents
• CPC Class Codes: H01M 2300/004 Three solvents
• 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 4/505 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 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/449 having a layered structure
• CPC Class Codes: H01M 50/489 Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• CPC Class Codes: H01M 6/10 with wound or folded electrodes
• 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

Abstract

The present invention relates to a nonaqueous electrolyte secondary battery, and more particularly to its separator, and it is an object thereof to prevent electrolyte leakage accident due to elevation of cell internal pressure even if the cell is exposed to high temperature without sacrificing the cell capacity.

To achieve the object, by using the polyolefin group separator large in endothermic calorie per unit area by the heat of fusion in a temperature range of 70 to 150° C., and selecting appropriate graphite powder for negative electrode and organic solvent in nonaqueous electrolyte, the electrolyte leakage accident can be successfully eliminated by suppressing the reaction between the cell active substance and organic solvent, thereby suppressing elevation of cell internal pressure.

Claims

1. A nonaqueous electrolyte secondary battery using a separator composed of a polyolefin group microporous membrane of 15 to 30 μ

m in thickness, with the endothermic calorie per unit area by the heat of fusion of at least 0.07 cal/cm² in a temperature range of 70 to 150°

C.

3. A nonaqueous electrolyte secondary battery of

claim 1

or

2

, wherein the positive active substance is a lithium contained transition metal oxide expressed in a formula LixMyO₂ (where M is at least one transition metal selected from the group consisting of Mn, Fe, Co and Ni, 0.5≦

x≦

1.0, 1.0≦

y≦

2.0).

4. A nonaqueous electrolyte secondary battery of

claim 1

or

2

, wherein the carbon material for negative electrode is at least one of artificial graphite or natural graphite powder with the plane interval (d₀₀₂) of (002) plane by X-ray diffraction of less than 3.380 Å

, and the specific surface area by BET method of 2.0 m²/g or more and less than 8.0 m²/g.

5. A nonaqueous electrolyte secondary battery of any one of

claims 1

to

4

, wherein the organic electrolyte as the nonaqueous electrolyte is prepared by dissolving a solute mainly composed of lithium hexafluorophosphate, in an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propionate, and ethyl propionate.

2. A nonaqueous electrolyte secondary battery using a polyethylene independent microporous membrane of 15 to 30 μ

m in thickness, with the endothermic calorie per unit area by the heat of fusion of at least 0.07 cal/cm² in a temperature range of 70 to 150°

C., or a multilayer hybrid membrane of said microporous polyethylene membrane and a microporous polypropylene membrane, as the separator.