Achieving a Double Advantage through Design of TiO2/C Interlaced Coating for Si Anode

Multifunctional coating strategy shows promising prospective in advancing Si-based anodes towards practical applications in Li-ion batteries. Dual coating of amorphous carbon and TiO2 shows demonstrable advantages owing to high elasticity of amorphous carbon and mechanical toughness of TiO2. However, for past design of Si@C@TiO2 composite electrode, wherein C and TiO2 are configured layer-by-layer, a long-standing problem exists as that a thin TiO2 coating is insufficient to stabilize the electrode’s architecture while a thick one prevents the core active material of Si far from fully electrochemically utilization due to the too strong structural constraint effect. Herein, it presents that a facial heat treatment of Si@C@TiO2 with thick enough TiO2 can readily avert the problem. Such a strategy promotes the capacity utilization rate from 39% to 61% for the initial cycle and from 43% to 85% after 200 cycles. Model structure of C/TiO2 multilayer films is employed to reveal the role of the heat treatment. It finds that the heat treatment can transform a layer-by-layer structure of C@TiO2 into an interlaced structure of C/TiO2 which exhibits a dual advantage in withstanding mechanical strain and simultaneously promoting Li-ion storage and electron/Li-ion transport.