▎ 摘　　要

NOVELTY - A composite material comprises carbon-coated iron oxide and nitrogen doped graphene, and graphite layer whose surface is uniformly distributed with iron(II,III) oxide. USE - Composite material used as cathode active material of lithium ion battery (all claimed). ADVANTAGE - The composite material has excellent cycle and rate performance, effectively buffers volume effect of iron oxide in the electrochemical reaction, improves the conductivity of the material, greatly reduces the impedance of the battery, and effectively improves the electrochemical properties of the material. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) preparation method of composite material; (2) application of composite material as cathode active material; and (3) lithium ion battery comprising anode active material and cathode active material.