▎ 摘　　要

NOVELTY - Graphene wrapped nano-meter silicon particle composite electrode material has 0.5-2microns diameter and 10-30microns length. The nano sized silicon particles are encapsulated in graphene roll of 30-100nanometer size. The mass fraction of nano meter silicon particles is 40-60%. USE - Graphene wrapped nano-meter silicon particle composite electrode material. ADVANTAGE - The graphene wrapped nano-meter silicon particle composite electrode material has enhanced structural stability, excellent electrical conductivity, high specific capacity, high-rate performance and high cycle stability. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing graphene wrapped nano-meter silicon particle composite electrode material, which involves: (A) separating oxidized graphite by Hummer method and dispersing oxidized graphite in deionized water 1: 10000 to 1: 200 mass ratio; (B) centrifuging oxidized graphite at 3000-5000rotations per minute for 10-60minutes to remove the un-stripped layer of oxidized graphite and retaining the upper layer of graphene oxide suspension; (C) weighing nano-meter silicon particles and graphite oxide in 1: 2 to 2: 1 ratio; (D) dispersing nano sized silicon particles in deionized water in 1:10000 to 1: 500 mass ratio; (E) adding polydiallyldimethylammonium chloride into the nanosilica suspension in 1: 10 to 1: 1 volume ratio and dispersing ultrasonically for 0.1-1hour so that polydiallyldimethyl ammonium chloride is uniformly attached to surface of nano-silicon particles with positive charge; (F) washing 3-5 times with deionized water to remove excess of polydiallyldimethylammonium chloride; (G) adding inally, deionized water to nanosilica particles treated with polydiallyldimethylammonium chloride to reach same volume as suspension of nanometer silicon particles; (H) mixing suspension of graphene oxide and the polydiallyldimethylammonium chloride treated nanosilica suspension obtained in 1: 2 volume ratio and ultrasonic mixing for 0.1 and 0.5hours; (I) heating the mixture to 50-100 degrees C and transferring to a plastic beaker; (J) placing the plastic beaker in liquid nitrogen and freeze-drying for 20-40 hours to obtain yellow powder; (K) heating the yellow powder to 600-800 degrees C in a hydrogen-argon mixed gas atmosphere at rate of 2-6 degrees C per minute for 1-3 hours and then cooling to room temperature with the furnace; (L) placing the black powder obtained in hydrogen fluoride solution having 5-10% mass concentration and soaking for 0.1-1 hour to remove silica; (M) centrifuging and washing with anhydrous ethanol 3-5 times to remove hydrogen fluoride; and (N) vacuum drying for 10-20 hours under at 50-100 degrees C to obtain graphene-wrapped nano silicon particles.