Molten salt electrolytic synthesis of silicon-copper composite nanowires with enhanced performances as lithium ion battery anode

A facile metallurgical method named molten salt electrolysis was introduced to prepare silicon nanowires (Si NWs) and Cu9Si/Si composite nanowires that were used as the anode materials for lithium-ion batteries (LIBs). Simply utilizing SiO2 and Cu/SiO2 mixture as the raw materials, by tailoring voltage into the molten salt chamber, SiO2 was constantly deoxidized to form Si flexible nanowires with 1-3 μm in length and 100-200 nm in width. Cu ingredient further catalyzed the growth of silicon nuclei to generate straight wires with longer 10 μm and narrower 60-100 nm. Benefiting from the compositional and structural advantages, the Cu9Si/Si nanocomposite anode exhibited a better capacity retention that delivered a specific capacity of 601.3 mAh·g−1 at 200 mA g−1 after 200 cycles and 398.8 mAh·g−1 at 500 mA g−1 after 500 cycles. Notably Cu9Si/Si NWs anode with enhanced rate capability was also obtained, with a specific capacity of 747.6 mAh·g−1, 550.6 mAh·g−1 and 412.2 mAh·g−1 at the current density of 200 mA g−1, 500 mA g−1 and 1000 mA g−1, respectively.