▎ 摘　　要

NOVELTY - Composite silicon material comprises matrix particles and first conductive material dispersed between the matrix particles, where the base particles comprise a silicon material and a coating layer covering a portion of the outer surface of the silicon material, the coating layer comprises aluminum oxide and a carbon material, and the first conductive material comprises graphene and/or conductive carbon tube. USE - Composite silicon material useful in lithium ion battery (claimed). ADVANTAGE - The composite silicon material improves the cycle performance and safety of the lithium ion battery on the basis of increasing the energy density of the lithium ion battery. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a lithium ion battery, comprising negative electrode sheet comprising negative electrode current collector and first negative electrode active layer arranged on the surface of the negative electrode current collector, where the first negative electrode active layer comprises carbon-based negative electrode active material and composite silicon material.