▎ 摘　　要

NOVELTY - Functionalized graphene composite material, comprises a graphene nanosheet, an array of carbon nanotube grown vertically on the graphene nanosheets, a polyelectrolyte that crosslinks the graphene nanosheets together, where the graphene nanosheet and the polyelectrolyte are connected by at least pi pi conjugate, a chemical bond, a hydrogen bond, and a van-der-waals force. USE - Used as functionalized graphene composite material. ADVANTAGE - The composite material prevents battery short circuit and coulomb efficiency reduction phenomenon. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) Preparing the composite material, comprising (i) utilizing chemical vapor deposition method and preparing surface vertically growing carbon nano-tube array of graphene nano-meter sheet to obtain the graphene/carbon nano-tube complex three-dimensional structure, and (ii) dispersing the graphene/carbon nano-tube complex three dimensional structure ultrasonic in water to obtain a dispersion, mixing the dispersion with aqueous polyelectrolyte;and (2) lithium battery system cathode material comprises cathode active material and functionalized graphene composite coated on the surface of the negative active material, where the cathode material of the lithium battery system has a core-shell structure, and the functionalized graphene composite material is the functionalized graphene composite material, and the cathode material of the lithium battery system is a lithium ion battery cathode material or a lithium polymer battery cathode material.