Highly Efficient Synthesis of Silicon Nanowires from Molten Salt Electrolysis Cell with a Ceramic Diaphragm

Silicon (Si) nanowire as a kind of one-dimensional semiconductor material is widely used in solar cells, biosensors, nanoelectronic devices, and lithium-ion batteries, among other applications. Traditional preparation methods for Si nanowires require high-purity substrates and metal catalysts. Herein, we report an efficient method of synthesizing Si nanowires by electrochemical reduction of CaSiO₃ in CaCl₂ molten salt. An electrolytic cell with a ceramic diaphragm is designed to separate the cathode and anode, which effectively avoids the migration and enrichment of oxygen and impurity ions. The ceramic diaphragm slows the diffusion of O²⁻ ions and is favorable to the formation of Si nanowires. Electron microscopy and XRD analysis reveal that the electrolytic products are mainly Si nanowires with a uniform size of 20-60 nm. The as-synthesized Si nanowires evaluated as an anode material for lithium-ion batteries deliver a reversible capacity of 886 mA h g^-1 after 150 cycles at 0.2 A g^-1.