Silicon nanowires with and without carbon coating as anode materials for lithium-ion batteries

Silicon nanowires (Si NWs) with and without carbon coating were successfully prepared by combination of chemical vapor deposition and thermal evaporation method. The morphologies, structures, and compositions of these nanomaterials were characterized in detail. Furthermore, the electrochemical performances of uncoated and carbon-coated Si NWs as anode materials were also studied. It shows that the carbon-coated Si NWs electrode has higher capacity, better cycle stability, and rate capability than the uncoated materials. For example, it delivers 3,702 and 3,082 mAh g(-1) in the initial charge and discharge processes. When cycled between 0.02 and 2.0 V at a current density of 210 mA g(-1), it yields a high coulombic efficiency of 83.2%. The discharge capacity still remains around 2,150 mAh g(-1) after 30 cycles.