Effect of synthesis methods on the electrochemical performance of perovskite‑type La_0.6Sr_0.4Co_0.2Fe_0.8O₃ as supercapacitor electrode material

Perovskite‑type La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF6428) was synthesized using sol–gel (Sol-LSCF6428) and glycine combustion (Gly-LSCF6428) methods. A comparative analysis was conducted on the microstructure, elemental valence states, specific surface area, and electrochemical properties of LSCF6428 produced by each synthesis route. Structural analysis confirmed that Gly-LSCF6428 exhibited superior crystallinity, optimized microstructure, abundant oxygen vacancies and mesoporous distribution and higher specific surface area. Electrochemical testing in a three-electrode setup with 1 M Na₂SO₄ electrolyte revealed that Gly-LSCF6428 outperformed Sol-LSCF6428. Gly-LSCF6428 achieves a specific capacitance of approximately 168 F g⁻¹ compared to 139 F g⁻¹ of Sol-LSCF6428 at 2 mV s⁻¹ scan rate. Gly-LSCF6428 also exhibits remarkable cycle stability of 99.4% retention after 5000 cycles(at 3 A g⁻¹). In a 6 M KOH electrolyte, the Gly-LSCF6428 electrode exhibits a high specific capacitance of 266 F g⁻¹ at a current density of 1 A g⁻¹, along with a low internal resistance (R_s = 0.48 Ω). In addition, the Gly-LSCF6428//Gly-LSCF6428 symmetric supercapacitor provides an energy density of 3.74 Wh kg⁻¹ at a power density of 500 W kg⁻¹. These findings suggest that the properties of LSCF6428 can be effectively tuned through synthesis methods, making it a promising candidate for energy storage applications.