Electrochemical Performance Enhancement of Nitrogen-Doped TiO2 for Lithium-Ion Batteries Investigated by a Film Electrode Model

Titanium dioxide (TiO2) is proposed as a promising anode material for lithium-ion batteries (LIBs) due to its highly stable structure and slight side reaction at the electrode/electrolyte interface. The low specific capacity and slow Li-ion diffusion kinetics are the major bottlenecks for the actual application of TiO2. It is thus important to exploit viable pathways to enhance the electrochemical performance and understand the corresponding mechanisms. In this work, high-quality amorphous TiO2 (TO) and anatase TiO2 (cTO) film electrodes are employed to investigate the bulk electrochemical performance by minimizing the surface contribution. At the same time, nitrogen (N) doping is performed for further comparison. The results show that TO has a relatively lower specific capacity than cTO. However, N-doped TO (TON) presents a specific capacity more than 4 times higher than TO and 3 times higher than cTO. TON also exhibits a significantly improved initial Coulombic efficiency (ICE) and a relatively higher Li-ion diffusion coefficient. Our study shows that the superior electrochemical performance of TON is correlated to the synergistic effects of the bulk pseudocapacitor and battery characteristics.