Assembling porous carbon-coated TiO₂(B)/anatase nanosheets on reduced graphene oxide for high performance lithium-ion batteries

Highlights: • Porous carbon-coated mixed-phase Titanium dioxide nanosheets/reduced graphene oxide composites are successfully fabricated. • Carbon coating has been achieved from organic components. • Mesopores are uniformly distributed throughout the whole TiO₂@C nanosheet. • Excellent cycling stability: the reversible capacity of 158.6 mAh g⁻¹ is achieved at the current density of 800 mA g⁻¹ after 500 cycles. - Abstract: Novel porous carbon-coated mixed-phase porous TiO₂ (TiO₂(B)/anatase) nanosheets/reduced graphene oxide composites (TiO₂@C/RGO) are successfully prepared through a facile one-pot solvothermal process followed by subsequent heat treatment in H₂/Ar. The as-formed composites have a hierarchical porous structure, involving an average pore size of 28.56 nm, a large pore volume of 0.589 cm³ g⁻¹ and a desired surface area (136.19 m² g⁻¹). When used as an anode material in LIBs, TiO₂@C/RGO exhibits stable cycling performance with a reversible capacity of 272.9 mAh g⁻¹ (with the second capacity retention of 151.1%) after 500 cycles at a current density of 100 mA g⁻¹, much higher than that of TiO₂@C (177.6 mAh g⁻¹, 123.9% of the discharge capacity in second cycle) and TiO₂ (75.1 mAh g⁻¹, corresponding to 96.5% of the original capacity). More impressively, the capacity of TiO₂@C/RGO can reach 158.6 mAh g⁻¹ after 500 cycles even at 800 mA g⁻¹ with Coulombic efficiency above 99.0%. The superior electrochemical performance of TiO₂@C/RGO may be attributed to its unique 3D hierarchical porous structures, the existence of carbon, large surface area and extremely reduced diffusion length.