LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery capable of suppressing the reduction of a capacity.

SOLUTION: The lithium ion secondary battery 20 has a winding group 7 and a nonaqueous electrolyte solution accommodated in a battery container 8. The winding group 7 has positive and negative electrode plates wound with a separator W5 between. A lithium manganate composite oxide is used for a positive electrode active material, and amorphous carbon is used for a negative electrode active material. A particle diameter ratio D(P)/D(N) of a mean primary particle diameter D(P) of the positive electrode active material and a mean primary particle diameter D(N) of the negative electrode active material is adjusted within a range of 0.8-1.2. The speed of the lithium ions to be inserted and removed with the positive electrode plate becomes almost the same as the speed of the lithium ions to be removed and inserted with the negative electrode plate.

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