Bismuth induced charge transfer strategy for boosting the electrochemical performances of Bi³⁺ doped CaSnO₃ perovskite for symmetric supercapacitor

Perovskite oxide of calcium stannate CaSnO₃ (CSO) and Bi-doped Bi_0.05Ca_0.95SnO₃ (BCSO) materials were successfully synthesized via a hydrothermal route followed by thermal treatment. The effect of bismuth doping (0.05 wt%) to the CaSnO₃ and the corresponding morphology, conductivity and the electrochemical properties were investigated as electrode material for supercapacitor application. Structural characterization confirmed the formation of single-phase orthorhombic structure of Bi_0.05Ca_0.95SnO₃. Microscopic image exhibited the growth of Bi_0.05Ca_0.95SnO₃ due to the incorporation of bismuth ion in CaSnO₃. Doping of bismuth improved the electrical conductivity and ion exchange interaction along Bi to Sn via oxygen bridge (Bi-O-Sn) networks, and that boost the pseudocapacitive process in Bi_0.05Ca_0.95SnO₃. Fabricated BCSO electrode showed maximum specific capacitance value of ~ 193 F/g and ~ 162.8 F/g at 5 mV/s and at 1.0 A/g, respectively. A symmetric split-cell (BCSO//BCSO) demonstrated a specific capacity of ~ 53.3 mAh/g at 10 mV/s and ~ 73.3 mAh/g at 0.5 A/g, while maintaining excellent capacity retention of ~ 94% of its initial value at 1.0 A/g after 2000 cycles. The cell attained a maximum energy density of ~ 88.0 Wh/kg at a power density of ~ 2.10 kW/kg under a current density of 0.5 A/g. This study opens a new path to enhancing the electrochemical performance of perovskite oxide-based materials for energy storage devices.