Ultrathin 2D Mesoporous TiO₂ /rGO Heterostructure for High-Performance Lithium Storage

Lithium-ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO₂ ), with a high theoretical capacity (335 mAh g^-1 ) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO₂ is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO₂ /reduced graphene (rGO) heterostructure is fabricated via a layer-by-layer assembly process. The synergistic effect of ultrathin mesoporous TiO₂ and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g^-1 at a current density of 200 mA g^-1 and excellent cycling stability, with a capacity of 245 mAh g^-1 maintained over 1000 cycles at a high current density of 1 A g^-1 . The in situ transmission electron microscopy analysis indicates that the volume of the as-prepared 2D heterostructures changes slightly upon the insertion and extraction of Li⁺ , thus contributing to the enhanced long-cycle performance.