Effect of Acid Leaching on Silicon Nanoparticles and Their Electrochemical Performance in Lithium-Ion Batteries

In this work, crystalline Si nanoparticles are synthesized on a large scale via a low temperature molten salt method. The crystal morphologies and electrochemical properties of the samples after HCl and HF leaching are studied in detail. The electrochemical properties of the as-produced silicon samples, which are used as anode materials in lithium-ion batteries (LIBs), are evaluated. The final product, which contains more Si and less SiO², improves cyclic stability because it buffers the volumetric effect of Si during lithiation/delithiation. The HF acid leach removes the impurity of SiO². However, the prepared sample exhibits lower electrochemical properties. The sample with a low SiO² content can deliver a capacity of 1503 mAh g⁻¹ after 50 cycles at a higher current density of 1 A g⁻¹, and the Coulombic efficiency is approximately 100%. However, the sample after HF acid leaching only delivers a discharge capacity of 389 mAh g⁻¹ at 1 A g⁻¹ after 50 cycles.