Silicate‐Mediated Electrolytic Silicon Nanotube from Silica in Molten Salts

Abstract Electrochemical preparation/processing of functional silicon from abundant silica is an ideal protocol to promote sustainability of energy sectors. Such an imperative task is challenged by poor electrical conductivity of Si/SiO 2 and inadequate mass diffusion of bulk silicon. Herein, a template‐free and one‐step preparation of silicon nanotubes (Si‐NT) from electrochemical reduction of silica in molten salts is reported. An in situ oriented growth of silicate nanorods (NRs) from silica is clarified as the key step to direct a self‐template evolution of Si‐NT from silica. The silicate‐mediated construction of Si‐based NT is versatile and successfully extended to prepare Si‐NT/graphite and Ti x Si y ‐NT. Benefitting from fast longitudinal motorways for fast transport of electrons and ions along/inside NTs, an energy consumption 30% lower than industrial silicon production is achieved. When evaluated as anode of lithium ion battery, the Si‐NT‐based electrodes show outstanding initial Coulombic efficiency and high reversible capacity. The silicate‐mediated construction of Si‐based NT integrates straightforward preparation and intriguing functionality of Si‐based materials, bridging a closed‐loop Si‐based energy infrastructure.