Fabrication and electrochemical evaluation of nano-silicon anode materials for energy storage application

In order to solve the inherent low conductivity and the volume expansion problems of the silicon anode material, a modified precipitation method using polyvinyl alcohol as the surfactant was developed to prepare nano-scale silicon particle anode materials in this paper. First, the nano-silica particles were prepared by controlling the surfactant content. Then they were reduced to nano-silicon particles by the magnesium thermal reduction method. The obtained samples were characterized by XRD, Raman, SEM, nitrogen adsorption and desorption and electrochemical performance tests. The results showed that the obtained nano-silicon particles were uniform in size and the average particle size was about 46 nm. Their initial discharge specific capacity was 2653 mAh·g⁻¹ at 500 mA·g⁻¹ and the relative initial coulomb efficiency was 90.3 %. Moreover, they still had a large discharge capacity of 1478 mAh·g⁻¹ after 100 cycles at 500 mA·g⁻¹. Even at a large current density of 2000 mA·g⁻¹, they still retained a high specific capacity of 816 mAh·g⁻¹, showing excellent cycle performance and rate capability.