Lithium ion secondary battery
AssigneeNEC Corporation
InventorSuguru Tamai
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Abstract
Provided is a lithium ion secondary battery that has improved cycle characteristics and employs a silicon material as a negative electrode active material. The lithium ion secondary battery according to the present invention comprises a negative electrode comprising at least a copolymer and a material comprising silicon as a constituent element, wherein the copolymer comprises a monomer unit based on an ethylenically unsaturated carboxylic acid alkali metal salt and a monomer unit based on an aromatic vinyl and the copolymer comprises an alkali metal constituting the alkali metal salt in an amount of 1000 mass ppm or more.
Claims12
A lithium ion secondary battery, comprising,
- a negative electrode comprising a binder and a negative electrode active material a material comprising silicon as a constituent element,
- wherein the binder is a copolymer of an aromatic vinyl and an ethylenically unsaturated carboxylic acid, and at least part of the ethylenically unsaturated carboxylic acid is an alkali metal salt, and
- the copolymer comprises an alkali metal constituting the alkali metal salt in an amount of 1000 mass ppm or more.
A method for manufacturing a lithium ion secondary battery, comprising the steps of:
- fabricating the electrode element by stacking a positive electrode and a negative electrode via a separator, and
- encapsulating the electrode element and an electrolyte solution into an outer package,
- wherein the negative electrode comprises a binder and a negative electrode active material comprising a material comprising silicon as a constituent element,
- wherein the binder is a copolymer of an aromatic vinyl and an ethylenically unsaturated carboxylic acid, and at least part of the ethylenically unsaturated carboxylic acid is an alkali metal salt, and
- the copolymer comprises an alkali metal constituting the alkali metal salt in an amount of 1000 mass ppm or more.
Dependencies are inferred from the claim text.