Lithium ion secondary battery

Abstract

A lithium ion secondary battery is disclosed in which an electrode assembly is accommodated in a battery container, the electrode assembly including a positive electrode having a positive electrode mixture layer containing a lithium transition metal composite oxide, a negative electrode having a negative electrode mixture layer for occluding/releasing lithium ions, and a separator disposed to inner and outer peripheries of the positive electrode and the negative electrode. The lithium ion secondary battery being charged with a non-aqueous electrolyte containing a lithium salt, wherein the relation shown by the following formula (I) is satisfied: 0.57<b×c/a<0.60  (I) assuming the area of the positive electrode mixture layer as a, the area of the separator as b, and the porosity of the separator as c.

Dependencies are inferred from the claim text.