NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, LITHIUM ION SECONDARY BATTERY WITH NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERY, AND MANUFACTURING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To improve the cycle characteristics of a lithium ion secondary battery.SOLUTION: The negative electrode for a lithium ion secondary battery comprises a negative electrode mixture layer which includes a high-density negative electrode mixture layer formed on a negative electrode current collector, and a low-density negative electrode mixture layer formed on the high-density negative electrode mixture layer. The electrode density of the high-density negative electrode mixture layer is larger than that of the low-density negative electrode mixture layer. The upper and side faces of the high-density negative electrode mixture layer are covered by the low-density negative electrode mixture layer; and the film thickness of the high-density negative electrode mixture layer is equal to or smaller than 50% of that of the negative electrode mixture layer. The lithium ion secondary battery comprises the negative electrode.