Enhanced pseudocapacitive properties of cobalt-doped manganese oxide electrode utilizing magnesium sulfate electrolyte for supercapacitors

This paper investigates the enhanced pseudocapacitive properties of cobalt-doped manganese oxide (Co-doped MnO₂) electrode in magnesium sulfate (MgSO₄) electrolyte for supercapacitor applications. Co-doped MnO₂ was synthesized on nickel foam through a controlled hydrothermal process and specific heat treatment parameters. This resulted in the transformation into α-MnO₂ with a 2 × 2 tunnel structure. Morphological investigation illustrates the presence of a hierarchical micro-flower structure with a substantial surface area and mesoporous distribution. The specific surface area of the Co-doped MnO₂ electrode significantly increased to 158 m² g⁻¹, compared to the pristine (bare MnO₂) electrode (80 m² g⁻¹). Electrochemical analyses revealed a specific capacitance of 527 F g⁻¹ at 1 A g⁻¹ in MgSO₄ (1 M), showcasing a 1.6 times improvement over Na₂SO₄ (1 M). The unique structure of the Co-doped MnO₂, combined with magnesium ions as efficient electron donors, contributes to superior charge-storage, making it a promising candidate for high-performance supercapacitors. Comprehensive characterizations, such as XRD, XPS, BET, SEM, GCD, and EIS, confirm the advantageous electrochemical performance and durability of the Co-doped MnO₂ electrode in MgSO₄ electrolyte.