▎ 摘　　要

NOVELTY - Preparing porous silicon/graphene composite cathode material using diatomite as raw material comprises e.g. (a) diatomite purification: heating the diatomite, annealing, removing organic matter, using alkaline solution of alkali, washing until it is neutral, then acid leaching, washing, and drying, (ii) preparing porous silicon: mixing magnesium reducing agent and diatomite, heating, cooling to room temperature, soaking, washing and drying, and (iii) porous silicon/graphene composite material: mixing porous silicon and carbon source, loading on catalyst, and is placing in a tubular furnace. USE - The composite cathode material is useful for lithium ion battery. ADVANTAGE - The method has scientific and reasonable preparation, simple and easy operation, low cost, friendly environment, strong practicability, wide source of raw material, and fully utilizes the graphene with excellent electrical conductivity and good mechanical performance, effectively improves the silicon-based material of the conductivity and the volume effect. The lithium ion battery has current density of 100 mA/g, after 100 times of circulation, and the reversible capacity can reach 609.4 mAh/g. DETAILED DESCRIPTION - Preparing porous silicon/graphene composite cathode material using diatomite as raw material comprises (a) diatomite purification: heating the diatomite to 700-900 degrees C at a heating speed of 5-20 degrees C/minute under the condition of normal pressure, annealing for 1-6 hours, removing organic matter, using alkaline solution of alkali with concentration of 0.005-0.1 mol/l for 2.5-6 hours, washing until it is neutral, then using 4-8 mol/l acidic solution at 95 degrees C acid leaching for 4-8 hours, finally washing, and drying at 80 degrees C to obtain the purified diatomite, (ii) preparing porous silicon: magnesium reducing agent and diatomite with a mass ratio of 1:0.5-1:3 to mix, heating to 600-850 degrees C under an inert atmosphere, and keeping the temperature for 2-6 hours, then cooling to the room temperature, then using acid solution with a concentration of 0.1-2 M, soaking for 12-18 hours, washing and drying to obtain porous silicon, and (iii) porous silicon/graphene composite material: mixing the porous silicon obtained in the step (ii) and the carbon source, loading on the catalyst, and is placing in a tubular furnace, protective gas flow rate is 150-250 standard cubic centimeter per minute (sccm), rising the temperature to 900-1100 degrees C at a speed of 5-20 degrees C/minute, the hydrogen flow rate is 10-20 sccm and annealing for 5-20 minutes, then pyrolyzing carbon source deposited graphene, the graphene under protective atmosphere cooling to room temperature.