Dual immobilization of porous Si by graphene supported anatase TiO/carbon for high-performance and safe lithium storage.

Smart surface coatings have been proven to be an effective strategy to significantly enhance the electronic conductivity and cycling stability of silicon-based anode materials. However, the single/conventional coatings face critical challenges, including low initial Coulomb efficiency (ICE), poor cyclability, and kinetics failure, etc. Hence, we proposed a dual immobilization strategy to synthesize graphene supported anatase TiO/carbon-coated porous silicon composite (denoted as PSi@TiO@C/Graphene) using industrial-grade ferrosilicon as lithium storage raw materials through the simple etching, combined with sol-gel and hydrothermal coating processes. In this work, the dual immobilization from the "confinement effect" of the inner TiO shell and the "synergistic effect" of the outer carbon shell, improves the kinetics of the electrochemical reaction and ensures the integrity of the electrode material structure during lithiation. Furthermore, the introduction of the graphene substrate offers ample space for dispersing and anchoring the Si-based granules, which in turn provides a stable 3D conductive network between the particles. As a result, the PSi@TiO@C/Graphene electrode delivers high reversible capacity of 1605.4 mAh g with 93.65% retention at 0.5 A g after 100 cycles (vs. 4th discharge), high initial Coulomb efficiency (82.30%), and superior cyclability of 1159.9 mAh g after 250 cycles. The above results suggest that the particle structure has great potential for applications in Si-based anode and may provide some inspiration for the design of other energy storage materials.