Fe-substituted SrCoO3 perovskites as electrode materials for wide temperature-tolerant supercapacitors

Sr-based perovskites represent enormous potential as supercapacitor electrode materials. However, the wide-temperature supercapacitor application for perovskite-based electrodes has not been studied yet. Thus, there is a pressing need for comprehensive research and investigation in the wide-temperature range to unlock the full capabilities of Sr-based perovskite and pave the way for its successful integration into versatile supercapacitor systems. In this study, SrCo1-xFexO3-δ (x = 0.05, 0.10, 0.15 and 0.20) were synthesized by solid-state sintering method, as oxygen-intercalated electrode materials for wide temperature-tolerant supercapacitors. SrCo1-xFexO3-δ contains orthogonal and monoclinic phases for x = 0.05 and x = 0.10, and a stable monoclinic phase can be obtained when the substitution amount is at least 15 %. The best electrochemical performance was obtained in x = 0.10, with a specific capacitance of 526.6 F g−1 at 1 A g−1. This can be attributed to the lowest resistance and richest oxygen vacancies of SrCo0.9Fe0.1O3-δ, which are conducive to oxygen-intercalated energy storage. The SrCo0.9Fe0.1O3-δ@CC//AC@CC supercapacitor device displays a working voltage of 1.6 V and a stable long-term cycle life with 85.71 % capacity retention after 5000 cycles. Furthermore, the temperature-dependent electrochemical characterization indicates an improvement of electrochemical performance for both electrode and device as temperature increases, which may be ascribed to the enhanced ion migration in the electrolyte. From 0 to 85 °C, the specific capacitance of SrCo0.9Fe0.1O3-δ@CC electrode increases from 91.8 to 1035.9 F g−1 at 1A g−1, and the energy density of the device also increases from 7.6 to 26.2 Wh kg−1 when the power density is 800 W kg−1.