纳米硅/石墨负极材料的炭包覆改性研究

硅颗粒的低负载量及其与石墨基体的弱相互作用严重制约了硅/石墨负极材料的商业化应用.本研究通过浓硫酸和高锰酸钾的氧化处理增大石墨基体的比表面积,利用十二烷基苯磺酸钠作为表面活性剂,改善纳米硅与氧化石墨湿法混合的均匀性,采用柠檬酸催化蔗糖碳源的水解,以便热解后在复合材料表面形成完整的炭包覆层.XRD与SEM分析表明,改进的...

Study on carbon coating modification of nano-silicon/graphite anode materials

Low loading amount of silicon particles and their weak interaction with the graphite matrix seriously restrict the commercial application of silicon/graphite anode materials.In this study,specific surface area of the graphite matrix is increased via the oxidation treatment with concentrated sulfuric acid and potassium permanganate.Sodium dodecyl benzene sulfonate is used as the surfactant to improve the wet mixing uniformity of the nano-Si particles and graphite oxides(GOs).Citric acid is employed to catalyze the hydrolysis of sucrose which serves as carbon source,in order to generate integrated carbon coatings on the silicon/graphite composite materials after the pyrolysis step.Herein,the results of X-ray diffraction(XRD)and scanning electron microscopy(SEM)measurements demonstrate that the improved carbon coating process can promote the reduction of GOs,obtain high graphitic Si/C composites,and realize the uniform dispersion of silicon particles in the graphite matrix.Owing to the synergistic effects,the resultant carbon-coated nano-silicon/graphite anode could retain a high specific capacity around 400 mAh/g after 100 cycles at the current density of 100 mA/g.The modification not only increases the specific capacity of the anode,but also effectively inhibits the volume expansion of silicon particles during the cycling process.