LITHIUM ION SECONDARY BATTERY

摘要

A lithium ion secondary battery (100A) has a negative electrode collector (241A) and a negative electrode active substance layer (243A) formed on the negative electrode collector (241A). The negative electrode active substance layer (243A) includes a graphite material and a binder. In addition, the weight ratio of natural graphite in the graphite material is at least 80% in a first area (A1) in the vicinity of the negative electrode collector (241A) in the negative electrode active substance layer (243A). Furthermore, the weight ratio of artificial graphite in the graphite material is at least 80% in a second area (A2) in the vicinity of the surface of the negative electrode active substance layer (243A).