Effect of Hydrogenation on the Electrochemical Performance of Anatase and Rutile TiO2 As Anode for Sodium-Ion Batteries

Abstract

Defect engineering, such as manipulating oxygen vacancies (OVs), which can alter the local structure and electronic properties of metal oxides, has attracted increasing attention for improving the charge-storage performance of electrode materials. In this work, a high-pressure hydrogenation method was developed to fabricate oxygen-deficient TiO2. Two TiO2 phases, namely rutile (TiO2-R) and anatase (TiO2-A), and their hydrogenated phases (denoted with the prefix “H”) are investigated as sodium-ion battery (SIB) anodes. The charge-discharge properties of both phases can be significantly enhanced via the hydrogenation treatment. The introduction of OVs increases the electronic and ionic conductivity of TiO2, and the disordered TiO2 provides more electro-active sites for sodiation/desodiation reactions. For the first time, electrochemcial properties of the H-TiO2-R and H-TiO2-A electrodes are systematically compared. The H-TiO2-A electrode exhibits an excellent high-rate capacity of 100 mAh g–1 at 10000 mA g–1 and great cycling stability of 80% capacity retention after 4500 cycles. The superior performance is well supported by a generalized gradient approximation Perdew-Burke-Ernzerhof density functional calculation. The proposed anode and material modification strategy have great potential for high-power and high-durability SIB applications.