▎ 摘　　要

NOVELTY - A nano-silicon/graphene composite material is prepared by (1) preparing graphite oxide using graphite flakes as raw materials by Hummers method, mixing ethyl orthosilicate solution with graphite oxide, ball-milling in high-pressure ball milling tank, reacting at 21-70 degrees C, cooling to room temperature, placing in water heating kettle, adding deionized water, reacting at 100-200 degrees C for 6-60 hours, immersing in 0.1 M dilute hydrochloric acid solution for 3-48 hours, suction-filtering, drying, placing product under protection of nitrogen or argon at a heating rate of 1-20 degrees C/minute, carbonizing, cooling, and grinding to obtain silicon dioxide/graphene composite material; (2) grinding composite material with metal hydride and heating to 350-800 degrees C; and (3) cooling to room temperature, soaking in 1 M dilute hydrochloric acid for 3 hours, soaking in 10% hydrofluoric acid for half an hour, washing with deionized water and alcohol thrice, suction-filtering, and vacuum-drying at 80 degrees C. USE - Preparation of nano-silicon/graphene composite material for use as negative electrode material for lithium ion battery (claimed). ADVANTAGE - The preparation method has a simple process and is environment-friendly and easy to implement. The obtained product maintains good morphology and excellent electrochemical performance as a negative electrode material for lithium ion batteries. The discharge capacity is close to 1000 mAh/g after cycling 100 times at a current density of 0.2 mAh/g. DETAILED DESCRIPTION - A nano-silicon/graphene composite material is prepared by (1) preparing graphite oxide using graphite flakes as raw materials by Hummers method, mixing ethyl orthosilicate solution with graphite oxide having mass fraction of 25-85%, placing in high-pressure ball mill tank, where mass ratio of mixture and grinding ball is 1:(10-80), evacuating, pumping carbon dioxide (CO2) into high-pressure ball mill tank until internal pressure reaches 60-150 bar, reacting at 21-70 degrees C and speed of 100-700 rpm for 0.5-48 hours, cooling to room temperature, releasing CO2 gas in the high-pressure ball mill tank, removing liquid from ball mill tank, placing in water heating kettle, adding deionized water, reacting at 100-200 degrees C for 6-60 hours, immersing in 0.1 M dilute hydrochloric acid solution for 3-48 hours, suction-filtering, drying, placing product under protection of nitrogen or argon at a heating rate of 1-20 degrees C/minute, carbonizing to 400-1000 degrees C, heat-preserving for 0.5-12 hours, cooling, and grinding to obtain silicon dioxide/graphene composite material; (2) under vacuum or protective atmosphere, grinding composite material with metal hydride and transferring mixture to closed reactor, heating to 350-800 degrees C at a heating rate of 0.2-20 degrees C/minute, and heat-preserving for 0.5-20 hours; and (3) cooling to room temperature, taking out product from reactor, soaking in 1 M dilute hydrochloric acid for 3 hours, soaking in 10% hydrofluoric acid for half an hour, washing with deionized water and alcohol thrice, suction-filtering, and vacuum-drying at 80 degrees C.