Patent ID: 9472809
Filing Date: 2016-10-18
CPC Classification: H01M,Y02E,Y02T

Claim Text:
1. A lithium ion secondary battery comprising an electrode, the electrode including an active material mix layer on both sides of a current collector and the active material mix layer further including active material particles, wherein the active material mix layer has a smaller void ratio in a current collector side region of the active material mix layer near the current collector and a surface side region of the layer near the surface of the active material mix layer than in an intermediate region between the current collector side region and the surface side region of the active material mix layer, the active material particles have a longer average actual circumferential length in the surface side region and the current collector side region than in the intermediate region, a proportion of the void ratio in the current collector side region and the surface side region to the void ratio in the intermediate region is in a range of 86% to 95%, and a proportion of the average actual circumferential length of the active material particles in the current collector side region and the surface side region to the average actual circumferential length of the active material particles in the intermediate region is in a range of 109% to 127%.