Preparation And Investigation Of Si/C Composite Anode Materials For Li-ion Batteries

Lithium-ion battery has caused extensive attentions. The application oflithium-ion battery are constantly expanding, from cell phones, digital cameras,laptops to electric cars as well as military products. The commercial lithium-ionbattery anode materials are graphite based materials with a theoreticalcapacity of372mAh/g. With the development of science and technology, thecapacity and rates performance of lithium-ion battery should be continuouslyimproved for the miniaturization of electronic goods and some large machine.High performance of lithium-ion battery is extremely important for thedevelopment of portable electronic devices, electric vehicles and other storagedevices. Variety novel anode materials with improved performance have beendesigned and prepared by many methods. By using mesoporous SBA-15andsilica fume as silicon source, several Si/C composite materials with improvedperformance were obtained.First, SBA-15was used as silica source for the preparation of Si/Ccomposite material. After a simple impregnation, carbonization, calcining,reduction and washing process, a mesoporous Si/C composite was obtained.The results show that the carbon content, the temperature of carbonization,the control of magnesium reduction process, and removal of MgO andunreduced SiO₂show great influence on the performance of the final products.Second, a silica fume was used as silicon source, the core-shell structureof Si/C composite is prepared by a solvothermal method or a roomtemperature polymerization. While, the performance is not as high as weexpected for the agglomeration of the product due to the pH of the solvent inthe polymerization process and ionic species in the solution. Althoughagglomeration is not observed for the polymerization at room temperature, theperformance of this product shows a low performance for the coated carbon is contact good with the silicon particles after reduction. Therefore, the SEIpassivation layer is not stable. While, the stability of the material has beenimproved. This method provides a new way for the development of novelsilicon based anode material.