Enhancements of the structures and electrochemical performances of Li4Ti5O12 electrodes by doping with non-metallic elements

This paper systematically explores the non-metallic element (F, Cl, Br, I, C and N) doping modification of lithium titanate oxide(LTO) electrode materials. C, N, and Br play a significant role in improving the electrochemical performance of lithium titanate, and each of them had different modification advantages. In terms of the structure changes of LTO, it was found that the C dopant significantly reduced the particle size and agglomeration between LTO particles, the Br dopant performed best in increasing the unit cell volume of the LTO, and the N dopant could form oxygen vacancies and a small amount of metallic TiN structure. In terms of electrochemical performance change of the LTO, the C dopant could effectively reduce the charge transfer resistance, the Br dopant could significantly improve the capacity at low rates(174.5 mAh g(-1) at 0.1 C; 172.3 mAh g(-1) at 0.5 ?degrees C), and the N dopant could greatly promote the high rate performance of LTO (compared with pure LTO, the capacity of N-LTO at 10 C and 20 ?degrees C, increased by 13.5% and 4.1%, respectively). The three dopants could induce different numbers of Ti3+ active sites, narrow the bandgap, and thereby thus facilitate the electron transport in the lattice of the LTO. This study provides new insights into optimizing the electrochemical performance of Li4Ti5O12 by adjusting the morphology, crystal structure, and electronic structure of lithium titanate based on the characteristics of non-metallic materials.