Systematic Study of Alkali Cations Intercalated Titanium Dioxide Effect on Sodium and Lithium Storage.

The fast development of electrochemical energy storage devices necessitates rational design of the high-performance electrode materials and systematic and deep understanding of the intrinsic energy storage processes. Herein, the preintercalation general strategy of alkali ions (A = Li+, Na+, K+) into titanium dioxide (A-TO, LTO, NTO, KTO) is proposed to improve the structural stability of anode materials for sodium and lithium storage. The different optimization effects of preintercalated alkali ions on electrochemical properties are studied systematically. Impressively, the three electrode materials manifest totally different capacities and capacity retention. The efficiency of the energy storage process is affected not only by the distinctive structure but also by the suitable interlayer spacing of Ti-O, as well as by the interaction effect between the host Ti-O layer and alien cations with proper size, demonstrating the pivotal role of the sodium ions. The greatly enhanced electrochemical performance confirms the importance of rational engineering and synthesis of advanced electrode materials with the preintercalation of proper alkali cations.