Highly reversible electrochemical magnesium/lithium insertion performance in TiO2(B) nanosheets with Ti cationic vacancies

Multivalent ion batteries show a promising future. As one of the crucial defects, cationic vacancies can improve diffusion coefficient and electronic conductivity and provide additional metal ions storage sites. Here, we prepare 2D cation-deficient TiO2(B) nanosheets (D-TiO2(B)) through the substitute of O by F. The D-TiO2(B) exhibits excellent properties of charge transfer and electrochemical kinetics. In the Mg-ion battery, the D-TiO2(B) electrode delivers a high reversible capacity of 129.4 mAh g(-1) at 100 mA g(-1) after 200 cycles. Furthermore, the DTiO2(B) electrode also displays high specific capacity, good long-cycling stability and rate capability in Li-ion battery. The improved electrochemical performance is attributed to the elevated diffusion coefficient, abundant energy storage sites and reduced interface resistance due to cation vacancies and F.

Automated summary

Multivalent ion batteries hold promise for future energy storage. This study demonstrates the enhanced electrochemical performance of 2D cation-deficient TiO2(B) nanosheets through the substitution of oxygen with fluorine. The resulting D-TiO2(B) exhibits improved charge transfer, diffusion coefficient, and electrochemical kinetics, leading to high reversible capacity, long-cycling stability, and rate capability in both Mg-ion and Li-ion batteries.