Preparation of Carbon–Silicon Composites by Thermal Decomposition of Silane and Their Electrochemical Performance

The traditional graphite electrode materials can’t meet the needs of the Li-ion batteries with high energy density because of its low specific capacity, it is of great practical significance to modify the traditional graphite electrode materials and improve their specific capacity. In this paper, a simple one-step method is used to recombine silicon onto the conventional graphite electrode materials, which greatly improves the specific capacity and the cycling performance of the electrode materials. When the content of silicon in the carbon–silicon (C/Si) composites is 10.5 wt %, the theoretical specific capacity of the obtained C/Si composites is 692.7 mA h/g, and after 1000 cycles of charge and discharge, the actual specific capacity is 580 mA h/g, which is about 81.8% of the theoretical specific capacity; when the content of silicon in the C/Si composites is 32.7 wt %, the theoretical specific capacity of the obtained C/Si composites is 1420.7 mA h/g, and after 1000 cycles of charge and discharge, the actual specific capacity can still reach 1050 mA h/g, which is about 73.9% of the theoretical specific capacity; when the content of silicon in the C/Si composites is 48.6 wt %, the theoretical specific capacity of the obtained C/Si composites is 1930.6 mA h/g, and after 1000 cycles of charge and discharge, the actual specific capacity is 745 mA h/g, which is about 38.6% of the theoretical specific capacity; therefore, the optimal content of silicon in C/Si composites is about 32.7 wt % in terms of battery performance and production costs. Through incorporating silicon into traditional graphite electrode materials via thermal decomposition of silane, the specific capacity of the negative electrode is improved significantly, which is a better way to upgrade the products of the traditional graphite negative electrode materials manufacturers.