Preparation And Electrochemical Properties Of Modified Graphite Anode Materials For Sodium Ion Battery

In this paper,the graphite oxide(GO-400、GO-600 and GO-800)was prepared by Hummers oxiding ball milling natural graphite,and the influence of ball milling speed(400 rpm、600 rpm、800 rpm)on the structure and electrical properties of graphite oxide was studied.As ball milling speed increases the layer spacing of graphite oxide showed a decreasing trend,cycle stability exhibit reduced after the first increase;GO-600 has the best cycling stability,after 20 weeks 96% of the capacity retention rate.GO-400 has a maximum initial discharge capacity,was 92.4 mAh/g.The graphite oxide was modified using 200 ℃ heat treatment.Graphite oxide after heat treatment becomes fluffy,interlayer spacing decreases(less than 0.382 nm),the initial discharge capacity and cycle stability has been improved.The reduced graphite oxide(RGO-600)from GO-600 after heat treatment had the best initial discharge capacity of 216.9 mAh/g;after 20 cycles,the capacity of was 208.6 mAh/g.In the end,the GO-400 with the largest layer spacing was selected to improve the electrochemical properties by the method of asphalt coating.It is found that the surface of the coated sample is smooth and the layer spacing is larger than that of the uncoated samples.BGO-20 whose coating amount is 20% had the highest first Kulun efficiency(89.7%)and the best rate performance,the capacity of 126.2 mAh/g under 200 mA/g;BGO-30 whose coating amount is 30% had the best cycle stability,its discharge capacity is 195.9 mAh/g after 20 cycles.