Investigation of Porous Silicon/Carbon Composite as Anodes for Lithium Ion Batteries

3D porous silicon was synthesized by metal-assisted chemical etching process using commercially available polycrystalline silicon powders. After chemical etching in optimized solution, 3D porous silicon structures with pore size of about 130 nm and specific surface area of about 4.85 m/g was obtained. Subsequently, the 3D porous silicon powders treated with ball milling and heat carbonization processes were coated with amorphous carbon and utilized as the anode electrode material for lithium ion battery. The combination of the 3D porous structure and a carbon coating layer can accommodate large mechanical strains by providing the empty space of the pores to alleviate the volume change, and by increasing the electrical conductivity with the carbon layer. The electrodes achieve an initial charge capacity of 3345 mAh/g with coulombic efficiency of 85.8% as well as a high reversible capacity of 1645 mAh/g after 55 cycles at 0.4 A/g. And it is capable to retain a capacity of 1174 mAh/g even at 4 A/g. Thus, this work introduces a novel and easy potential industrial method for fabrication Si/C materials for high-performance lithium ion battery.