Improved Li-ion diffusion process in TiO₂/rGO anode for lithium-ion battery

The low diffusion rate of pure TiO₂ affects the inferior electrochemical performance such as cycling capacity and rate capability. Many works have been focusing on the material structural control to solve this problem, but the specific mechanism of the electrochemical process still needs further study. In this paper, we prepare titanium dioxide/reduced graphene oxide (TiO₂/rGO) hybrids to comprehend the improved diffusion rate by using electrochemical kinetics characterization. Compared with pure TiO₂, the TiO₂/rGO hybrids have a reduced particle size and layer-shaped structure. For electrochemical test, the TiO₂/rGO assembly exhibits high rate capability (∼270 mAh g⁻¹ at 0.1 A g⁻¹), and excellent cycling capacity (∼180 mAh g⁻¹ at 0.5 A g⁻¹ after 2000 cycle). Studying the electrochemical reaction process finds that the charge transfer rate of titanium oxide were significantly increased due to the addition of graphene oxide. A diffusion controlled behavior of Li⁺ is found to dominate the charge-discharge process in TiO₂/rGO hybrids, rather than the capacitive process of the pure TiO₂ electrode. This dominated diffusion is believed to inspire both of superior rate and capacity of the TiO₂/rGO hybrids in this work. - Highlights: • Graphene coated TiO₂ nanoparticles were synthesized for Lithium battery. • The reversible rate capability and cycling capacity are improved. • Analyze the difference between diffusion controlled and capacitance controlled charge-discharge process.