Oxygen vacancy boosted the electrochemistry performance of Ti⁴⁺ doped Nb₂O₅ toward lithium ion battery

In this study, oxygen-deficient orthorhombic niobium oxide (T-Nb₂O₅) has been synthesized via a facile solid-state reaction method. The strategies of Ti⁴⁺ doping and being annealed in the reducing atmosphere can introduce oxygen vacancies to Nb₂O₅ (denoted as NTAH). When being tested as lithium ion batteries' anode, the obtained NTAH electrode shows obvious improved electrochemical performances with high specific capacity and superior cycling stability. Specifically speaking, a high reversible capacity of above 178 mA h g^{− 1} has been retained after 500 cycles at the current density of 200 mA g^{− 1}. In addition, NTAH electrode can maintain a specific capacity of 63 mA h g^{− 1} after 500 cycles at the current density of 2A g^{− 1}. EIS and CV measurement reveal that the intentionally introduced oxygen vacancies into T-Nb₂O₅ can improve the conductivity of electrodes and increase the active sites for redox reaction. At the same time, the merit of intercalation reversible mechanism can ease the volume variation of T-Nb₂O₅ during cycling process and consequently an enhanced electrochemical performance can be expected.