Engineering electronic structures of titanium vacancies in Ti1-xO2 nanosheets enables enhanced Li-ion and Na-ion storage

Abstract Up to now, three kinds of ion-storage mechanisms are summarized towards anode materials in lithium/sodium-ion batteries, but they have low capacity and poor cyclic performance. Therefore, it is necessary to develop a new approach to optimize ion storage. Herein, we report an adsorption/desorption storage route through engineering electronic structure of cation-deficient Ti1-xO2 nanosheets. Ti1-xO2 nanosheets indeed exhibit higher capacity (332.1 mA h g-1 vs. 137.7 mA h g-1 for LIBs, 195.7 mA h g-1 vs. 111 mA h g-1 for SIBs), and more stable cyclic performance (296 mA h g-1 vs. 99 mA h g-1 for LIBs, 178.1 mA h g-1 vs. 80.2 mA h g-1 for SIBs after 100 cycles) at 0.1A g-1 than TiO2 nanosheets. Kinetics analysis and density functional theory (DFT) calculations reveal that electronic structures of vacancy within Ti1-xO2 nanosheets encourage a novel adsorption-desorption storage route. These results highlight the benefits of the engineered electronic structures within electrode material and implement novel ion-storage mechanism towards broad energy storage applications.