Lithium ion secondary battery

Abstract

A lithium ion secondary battery includes an electrode assembly configured such that positive and negative plates are wound or stacked with a separator interposed therebetween. The positive plate is configured such that positive-electrode mixture layers are formed on both surfaces of a positive-electrode current collector. The negative plate is configured such that negative-electrode mixture layers are formed on both surfaces of a negative-electrode current collector. The positive-electrode mixture layers formed on the positive plate each have a larger porosity than the negative-electrode mixture layers formed on the negative plate. A more refractory porous layer 1 than the separator is formed between the negative plate and the separator. The porous layer is made of a material for retaining an electrolyte.

Dependencies are inferred from the claim text.