Synergistic storage of lithium ions in defective anatase/rutile TiO2 for high-rate batteries

Abstract

Fabrication of heterostructured materials is a strategy to boost the charge-transfer kinetics and the performance of high-rate lithium storage. Here, a facile, low-temperature method for the synthesis of high-area TiO<inf>2</inf> nanospheres containing both anatase and rutile phases is described. The as-prepared materials contain a high concentration of oxygen vacancies facilitating electron conduction in the anatase phase and theoretical calculations provide evidence of a low energy barrier for Li⁺ transport in the rutile phase. The synergy between the two phases renders the shared conduction of electrons through anatase and Li⁺ ions via rutile at high-current rates, leading to the anodes that outperform the alternate TiO<inf>2</inf> systems when the combination of capacity at high current densities and cycle stability are considered, displaying a capacity of 95.4 mAh g⁻¹ at 10 A g⁻¹ and a 97.2% retention of capacity over 500 cycles at 1 A g⁻¹.