Plasma-induced oxygen vacancy in amorphous titanium oxides for excellent sodium storage

The structure of titanium oxide is relatively stable, but its specific capacity is low. Rational design of the structure to promote rapid electron/ion migration is crucial for achieving excellent electrochemical performance of titanium oxide. Herein, we present an easy technique for creating oxygen vacancies in amorphous spherical titanium oxide (a-TiO2-x) through Ar/H2 plasma treatment. The as-prepared TiO2-x electrode exhibited remarkable electrochemical performance with an initial charge capacity of 262.0 mAh g−1, significantly superior to that of a-TiO2 (160.3 mAh g−1). Moreover, the TiO2-x electrode demonstrated excellent cycle performance, maintaining a high reversible capacity (286.8 mAh g−1 after 50 cycles), notably surpassing a-TiO2 (198.0 mAh g−1). Experimental and DFT calculations revealed that a-TiO2-x markedly facilitated Na + diffusion rate, increased electron conduction, and then attained outstanding rate performance (152.3 mAh g−1 at 1000 mA g−1) and cycling performance (195.1 mAh g1 at 500 mA g−1 after 500 cycles). This work indicates that plasma treatment provides a novel and universal strategy for developing alternative high-capacity anode materials.