BINDER FOR LITHIUM ION SECONDARY BATTERY NEGATIVE ELECTRODE, AND LITHIUM ION SECONDARY BATTERY WITH BINDER FOR NEGATIVE ELECTRODE

摘要

PROBLEM TO BE SOLVED: To resolve the problem that in the case of using a polyacrylic acid-containing binder, the binder itself makes a resistance because of its high coverage on a negative electrode active material, which worsens the load characteristic.

SOLUTION: The binder for a negative electrode comprises: a copolymer of an acrylic acid and a styrene sulfonic acid alkali metal salt. The styrene sulfonic acid alkali metal salt decreases the electrode internal resistance and improves the load characteristic because it has a high ion conductivity. In addition, the styrene sulfonic acid alkali metal salt is a neutralization-type monomer, and therefore it reduces carboxyl groups to react with Li ions and decreases the irreversible capacity, whereby the initial efficiency and charge and discharge capacities are increased.

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