SrCoO3-based perovskites with enhanced electrochemical performance through structural tailoring induced by B-site substitution

Abstract

The progression of supercapacitor technology hinges on the discovery of high-performance electrode materials to enhance energy storage. SrCoO3-δ perovskite holds considerable promise potential as an anion intercalation electrode material. To elucidate the structural and electrochemical performance modulation rules of SrCoO3-based perovskites, this study synthesized SrCo0.875M0.125O3-δ (M = Ti, Ta, Nb, Fe) perovskites with different B-site ion substitutions. The structural tailoring induced by B-site substitution were thoroughly investigated alongside their corresponding electrochemical performance. Notably, SrCo0.875Ti0.125O3-δ exhibited a simple cubic structure, while the other samples displayed a tetragonal structure. Additionally, SrCo0.875Fe0.125O3-δ displayed numerous oxygen vacancies and significant distortion in the [CoO6] octahedron, which is attributed to the lower valence state of Fe. At a current density of 1 A g−1, the specific capacities of SrCo0.875M0.125O3-δ (M = Nb, Ti, Fe, Ta) perovskites were 984.43, 853.33, 503.53, and 452.00C/g, respectively. SrCo0.875Nb0.125O3-δ demonstrated the highest specific capacity and capacity retention rate across various current density, owing to its relatively stable structure with appropriate oxygen vacancies and multivalent state changes of Nb. In contrast, SrCo0.875Fe0.125O3-δ, with excessive oxygen vacancies and severe structural distortions, exhibited restricted electrochemical performance, particularly at higher current densities. Integrating structural and performance analysis, this work proposes an optimization strategy for the electrochemical performance of SrCoO3-δ-based perovskite electrode materials, emphasizing the importance of tailoring multivalent B-site elements to achieve a stable perovskite structure with appropriate oxygen vacancies.