Electrochemical Performance of Sandwich-like Structured TiO2/graphene Composite as Anode for Potassium-ion Batteries

The TiO2/graphene composite was synthesized by a simple hydrothermal reaction combined with a post high-temperature sintering in an inert atmosphere using graphene oxide (GO), butyl titanate and NaOH as raw materials. The TiO2/graphene composite is composed of mesoporous graphene nanosheets and dispersive TiO2 nanoparticles that are attached to the surface and reside in the interlayer of graphene. Benefiting from the special microstructure and synergetic effects of electroactive materials TiO2 and graphene, TiO2/graphene composite is superior in charge capacity, rate capability and cycle performance to both graphene and TiO2. As anode materials for potassium-ion batteries, TiO2/graphene, graphene and TiO2 present initial charge capacities of 336.8, 261.9 and 30.3 mAh g-1 at 100 mA g-1, respectively, and maintain 245, 135.5 and 18.5 mAh g-1 after 100 cycles, respectively. Even at a high current density of 600 mA g-1, the remaining charge capacity of TiO2/graphene is 120 mAh g-1 after 100 cycles, significantly higher than those of graphene (50.7 mAh g-1) and TiO2 (4.5 mAh g-1).