Metal oxyacid salts-confined pyrolysis towards hierarchical porous metal oxide@carbon (MO@C) composites as lithium-ion battery anodes

Transition metal oxides (TMOs) have been thought of potential anodic materials for lithium-ion batteries (LIBs) owing to their intriguing properties. However, the limited conductivity and drastic volume change still hinder their practical applications. Herein, a metal oxyacid salts-confined pyrolysis strategy is proposed to construct hierarchical porous metal oxide@carbon (MO@C, MO = MoO₂, V₂O₅, and WO₃) composites for solving the aforementioned problems. A water-evaporation-induced self-assembly mechanism has been put forward for fabricating the MO@polyvinyl pyrrolidone (PVP)@SiO₂ precursors. After the following pyrolysis and etching process, small MO nanoparticles can be successfully encapsulated in the hierarchical porous carbon framework. Profiting from the synergistic effect of MO nanoparticles and highly conductive carbon framework, MO@C composites show excellent electrochemical properties. For example, the as-obtained MoO₂@C composite exhibits a large discharge capacity (1513.7 mAh·g⁻¹ at 0.1 A·g⁻¹), good rate ability (443.5 mAh·g⁻¹ at 5.0 A·g⁻¹), and supernal long-lived stability (669.1 mAh·g⁻¹ after 1000 cycles at 1.0 A·g⁻¹). This work will inspire the design of novel anode materials for high-performance LIBs.