锂离子电池用高容量硅/碳复合负极材料（英文）

High Reversible Capacity Si/C Composite Anodes for Lithium-Ion Rechargeable Batteries

通过镁和氧化亚硅之间的氧化还原反应制备细硅,并采用湿法混料及高温热解法合成了锂离子电池用硅/石墨/裂解碳复合负极材料。利用XRD、SEM、电化学测试考察了复合材料的结构与电化学性能,并结合循环伏安和电化学阻抗技术研究了复合材料的电化学可逆性和动力学性能。结果表明:制备的复合材料首次可逆容量为880 mAh/g,循环40次后为780 mAh/g,容量保持率可达88.6%,该方法显著改善了硅基材料作为锂离子电池负极材料的电化学性能。性能的提高主要归因于纳米结构的硅均匀分散在碳基体中,很好地抑制了充放电过程中的体积效应,同时石墨和裂解碳也充分保证了复合材料良好的导电性。

A high reversible capacity Si/C composite was synthesized by a thermal pyrolysis of citric acid embedded with finegraphite and silicon powders. The silicon was produced via an in-situ redox reaction between Mg and SiO. The structure, themorphology and the electrochemical performance of the materials were investigated by X-ray diffraction （XRD）, scanningelectron microscope （SEM）, electrochemical tests, cyclic voltammetry （CV） and electrochemical impedance spectroscopy（EIS）. Compared with the pristine silicon, the as-prepared composite exhibits much better electrochemical properties, whichhas a high reversible capacity of 780 mAh·g-1 at the 40th cycle with a retention up to 88.6%. The improved performance ismainly attributed to the uniform distribution of Si nanoparticles within the carbon matrix with buffering effect and excellentelectric conductivity.