Enhancing the Electrochemical Energy Storage Performance of Bismuth Ferrite Supercapacitor Electrodes via Simply Induced Anion Vacancies

Increasing the content of anion vacancies may yield significant improvement in the overall electrochemical energy-storing performance of perovskite materials, where the vacancy sites act as highly favorable ion diffusion paths. However, a detailed study on energy storage mechanism at binary cation sites under the anion deficiency should be further explored in supercapacitor electrode materials. In this study, a simple hydrothermal method and hydrogen gas exposure processes were used to generate oxygen vacancies in the crystal of BiFeO3 (BiFeO3-X) to enhance the overall electrochemical properties. At a current density of 1 A g-1, the BiFeO3-X supercapacitor electrode exhibits a large specific capacitance (461.9 F g-1, 923.8 mF cm-2, and 145.3 mAh g-1) and a high cycling stability (94.4%) after 2,000 cycles. Electrochemical analysis reveals that the oxygen vacancy sites can further increase the electrochemical activity of Bi sites, which is mostly suppressed in the pure crystal lattice, resulting in synergistic energy storage behavior of binary cation sites.