Silicon is an extremely important technological material, but its current industrial production by the carbothermic reduction of SiO2 is energy intensive and generates CO2 emissions. Herein, we developed a more sustainable method to produce silicon nanowires (Si NWs) in bulk quantities through the direct electrochemical reduction of CaSiO3 , an abundant and inexpensive Si source soluble in molten salts, at a low temperature of 650 °C by using low-melting-point ternary molten salts CaCl2 -MgCl2 -NaCl, which still retains high CaSiO3 solubility, and a supporting electrolyte of CaO, which facilitates the transport of O2- anions, drastically improves the reaction kinetics, and enables the electrolysis at low temperatures. The Si nanowire product can be used as high-capacity Li-ion battery anode materials with excellent cycling performance. This environmentally friendly strategy for the practical production of Si at lower temperatures can be applied to other molten salt systems and is also promising for waste glass and coal ash recycling.
Keywords: Li-ion batteries; electrolysis; molten salts; silicon nanowires; supporting electrolytes.
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