Hierarchically Porous and Conductive Interface via the rGO-TiO ₂ Framework Enabling a High-Performance Silicon Anode

Silicon (Si) has attracted much attention as a Li-storage anode material with high theoretical capacity but suffers from severe volume expansion, uncontrolled solid electrolyte interface (SEI) formation, and poor conductivity. Herein, we fabricate a Si-based composite where Si nanoparticles are encapsulated in rGO-modified 3D hierarchically macroporous/-mesoporous TiO2 (Si/rGO@3DHP-TiO2). TiO2 not only can suppress Si volume expansion and induce the generation of a thin and stable SEI film to prolong electrode lifespan but also can maintain structural integrity. The hierarchical pores enable efficient electrolyte/Li+ diffusion, while reduced graphene oxide in the TiO2 framework provides abundant conductive interfaces, enhancing electron transport. This Si/rGO@3DHP-TiO2 anode achieves a high-rate performance of 741.6 mAh g–1 at a high current density of 5 A g–1, and its capacity remains at 645.7 mAh g–1 over 1000 cycles at 2 A g–1. Furthermore, the assembled Si/rGO@3DHP-TiO2//active carbon Li-ion hybrid capacitors can attain a high Max. energy/power density of 152.1 Wh kg–1/10191.1 W kg–1, along with 91.2% capacitance retention over 10,000 cycles at 1 A g–1. The full battery assembled with a LiFePO4 cathode exhibits a capacity retention of 91% after 500 cycles at 1 C. This design strategy thus holds great promise for the rational construction of high-performance Si-based anodes, offering valuable insights for advancing next-generation Li-ion energy storage systems.