Silicon/Mesoporous Carbon/Crystalline TiO₂ Nanoparticles for Highly Stable Lithium Storage

A core-shell-shell heterostructure of Si nanoparticles as the core with mesoporous carbon and crystalline TiO₂ as the double shells (Si@C@TiO₂) is utilized as an anode material for lithium-ion batteries, which could successfully tackle the vital setbacks of Si anode materials, in terms of intrinsic low conductivity, unstable solid-electrolyte interphase (SEI) films, and serious volume variations. Combined with the high theoretical capacity of the Si core (4200 mA h g^-1), the double shells can perfectly avoid direct contact of Si with electrolyte, leading to stable SEI films and enhanced Coulombic efficiency. On the other hand, the carbon inner shell is effective at improving the overall conductivity of the Si-based electrode; the TiO₂ outer shell is expected to serve as a rigid layer to achieve high structural stability and integrity of the core-shell-shell structure. As a result, the elaborate Si@C@TiO₂ core-shell-shell nanoparticles are proven to show excellent Li storage properties. It delivers high reversible capacity of 1726 mA h g^-1 over 100 cycles, with outstanding cyclability of 1010 mA h g^-1 even after 710 cycles.