热解温度对锂离子电池Si/C复合负极材料性能的影响

Influence of Thermal Decomposition Temperature on Properties of Si/C Composites for Lithium-ion Batteries

以酚醛树脂为碳源,采用球磨-热解工艺制备了一系列Si/C复合负极材料,通过XRD、SEM、恒流充放电等测试方法,研究了热解温度对复合材料结构、形貌和电化学性能的影响。结果表明,前驱物经不同的热分解温度得到的复合负极材料,其衍射峰基本与原料硅和石墨的衍射峰相符。随着热分解温度的升高,硅颗粒的分散性得到改善,并与石墨及无定形碳层交错起来形成微孔结构,直接对复合材料的电化学性能产生较大的影响。当热分解温度为1000℃时,合成的Si/C复合负极材料综合电化学性能较好,首次充放电效率可以达到73.1%,以100mA/g放电,循环100周后容量保持率为89.7%,以200mA/g放电,循环100周后容量保持率仍可以达到87.8%。

A series of Si/C composite cathode materials were prepared by ball milling and thermal decomposi- tion process with phenolic resin as carbon source. Influence of thermal decomposition temperature on structures,mor- phology and electrochemical properties of the composites were studied through XRD, SEM and constant current charge discharge test method. The results show that the composite cathode materials were obtained by precursors du- ring different thermal decomposition temperature,whose diffraction peaks are similar to diffraction peaks of raw mate- rial of silicon and graphite. Increasing the heat decomposition temperature,the dispersion of the silica particles was im- proved, and they were staggered to form a porous structure together with graphite and amorphous carbon layer, which directly produce great influence on electrochemical properties of materials. When the thermal decomposition tempera- ture is 1000 ℃, the comprehensive electrochemical properties of Si/C composite cathode material synthesis is better. The first charge discharge efficiency can reach 73. 1%. After 100 cycles, the capacity retention rate is 89. 7% at 100 mA/g,87. 8% at 200 mA/g.