双层碳包覆SiO_(x)负极材料及其电化学性能研究

Electrochemical Performance of Dual⁃Layer Carbon⁃Coated SiO_(x) Anode Materials

为了解决氧化亚硅负极材料导电率低及循环性能差的问题,以聚丙烯酰胺(PAM)为液相碳源进行一次碳包覆,再通过化学气相沉积以甲烷混乙炔为气相碳源进行二次包覆,制备了具有含氮碳层的双层包覆氧化亚硅负极材料(SiO_(x)@DC-N)。与纯气相包覆(SiO_(x)@GC)以及纯液相包覆(SiO_(x)@LC)的氧化亚硅负极材料相比,SiO_(x)@DC-N展现出优异的倍率性能与循环性能,在4C(1C=1500 mA/g)的电流密度下比容量达850.1 mAh/g,以5∶95混合石墨后制成18650圆柱电池,其在电流密度1C充放电700圈循环后容量保持率仍有92.70%。

To address the problems of low conductivity and poor cycling performance of silicon oxide as negative electrode material,polyacrylamide(PAM)was adopted as a carbon source for the first carbon coating,and the methane-acetylene mixture was used as a gas-phase carbon source for the second coating by chemical vapor deposition to prepare nitrogen-containing double-layer carbon-coated silicon oxide anode materials(SiO_(x)@DC-N).Compared with pure gas-phase coated(SiO_(x)@GC)and pure liquid-phase coated(SiO_(x)@LC)silicon oxide anode material,SiO_(x)@DC-N exhibits excellent rate performance and cycling stability,showing that the specific capacity is 850.1 mAh/g at a current density of 4C(1C=1500 mA/g).The 18650 cylindrical batteries prepared by using a mixed graphite in a ratio of 5∶95 can have a capacity retention rate of 92.70%after 700 cycles of charging and discharging at a current density of 1C.