Effect of Co²⁺ and Mn³⁺/Mn⁴⁺ ratio on high-performance supercapattery

The growing demand for advanced energy storage highlights supercapacitors for their high power density and long cycle life. Supercapatteries are hybrid supercapacitors (HSCs) that combine carbon materials as anode and metal oxides as cathode with a battery-type behavior. Here, electrode materials of Co-doped MnO_x nanorods were prepared via incipient wet impregnation. The synthesis induced morphological modifications in the material and the creation of oxygen vacancies was suggested by their Mn³⁺/Mn⁴⁺ ratio. The 4.79 wt.% Co/MnO_x electrode delivered a high specific capacitance of 1478.52 F g⁻¹ at 1 A g⁻¹ and enhanced stability after 1000 cycles for a symmetric device. Then, the supercapattery reached 452.19 F g⁻¹ at 1 A g⁻¹, energy density of 579 Wh kg⁻¹, power density of 2881 W kg⁻¹, and good stability up to 1500 cycles. This study sheds light on the easy and low-cost production of a Co-doped MnO_x electrode material for enhanced energy storage.