Cr-Substituted SrCoO3-δ Perovskite with Abundant Oxygen Vacancies for High-Energy and Durable Low-Temperature Antifreezing Flexible Supercapacitor

Developing high-performance electrodes for flexible antifreezing energy storage devices has been a significant challenge with the increasing demand for portable components. In this work, Cr-substituted SrCoO_3-δ perovskites were first proposed as potential low-temperature supercapacitor electrode materials. The high-valence Cr⁶⁺ ([Ne]3s²3p⁶) substitution favors a high-spin state of Co ions with enhanced electronic repulsion effect, ultimately forming a stable cubic structure with high conductivity. Accordingly, the modification strategies of SrCoO₃ through the p6 configuration cation substitution have been improved. As a result, the asymmetric SrCo_0.95Cr_0.05O_3-δ@CC//PPy@CC device exhibited a high energy density of 44.90 Wh kg^-1 at 902.01 W kg^-1 and maintained a 95.8% specific capacitance after 10,000 cycles, demonstrating an ultralong cyclic stability. The dramatically improved electrochemical performance was attributed to the stabilized crystal structure, increased oxygen vacancy, and accelerated oxygen diffusion rate. Furthermore, a quasi-solid-state supercapacitor with ethylene glycol (EG)-modified KOH/PVA organohydrogel electrolyte was developed through an advance in situ-integrated strategy. After bending at 180° for 1000 cycles, only a 9.7% capacity decay was observed. Even under -40 °C, the supercapacitor has a large energy density of 46.94 μWh cm^-2. The present work represents the initial investigation into utilizing perovskite materials for antifreezing energy storage device, thereby confirming their potential application as low-temperature electronic components.