Ti1-xSnxO2 phase separation modulated electronic structure and kinetic behaviors for high-rate and long-cycle anodes

Abstract

TiO2 is a highly promising anode material for lithium-ion batteries with a high rate and long-term cycle performance. However, it exhibits a frustrating conductivity, similar to other oxide electrodes, along with triggered poorer rate and long cycle performance. Herein, a strategy combining atomic substitution and nanoengineering is proposed for the preparation of Ti1-xSnxO2 solid solution hollow spheres. Not only the electrochemical properties are modulated but also the electrochemical mechanisms are further considered. As a result, the Ti0·85Sn0·15O2 electrode achieves superior rate and cycling properties, achieving a specific capacity of 178.5 mAh g−1 at current densities up to 20 C (1 C = 335 mA g−1), maintaining 314.6 mAh g−1 after 1100 cycles at 3 C and 129.1 mAh g−1 after 1500 cycles at 10 C. Theoretical simulations and experimental investigations reveal that Ti1-xSnxO2 electrochemical phase separation, not an atomic substitution, is an indispensable factor in enhancing electrochemical properties. Ti1-xSnxO2 electrochemical phase separation to build TiO2/SnO2 heterojunctions, modulating the electronic structure near the Fermi energy level to enhance electrical conductivity and reduce Li+ migration energy barriers. This work on the optimization of electrochemical properties and electrochemical mechanisms will facilitate the promotion of the development of advanced energy storage systems.