Inverse spinel cobalt manganese oxide nanosphere materials as an electrode for high-performance asymmetric supercapacitor

In energy storage devices, it is critical to further develop spinel structured functional materials with rich redox-active sites and high theoretical capacitance. In this study, the nanosphere-shaped Cobalt Manganese Oxide inverse spinel structure was prepared by polyvinylpyrrolidone-assisted hydrothermal technique followed by calcination at 300 °C. Benefitting from the small nanosphere architecture, the Cobalt Manganese Oxide exhibits a high specific surface area to offer more redox-active sites and has a highly porous nature to shorten the ion movement pathway. The obtained Cobalt Manganese Oxide nanospheres exhibit a battery-like energy storage mechanism with a specific capacity (580 C g−1 at 5 mV s−1), high rate capability, and long-term cyclic stability performance (91.2% at 100 mV s−1 for 5000 cycles) in 6 M KOH electrolyte. The fabricated asymmetric supercapacitor device displays a high energy density of 29.1 Wh kg−1 at a power density of 320 W kg−1, and a power density of 3840 W kg−1 at an energy density of 4.4 Wh kg−1 with cyclic stability of 96.5% after 10,000 galvanostatic charge/discharge (GCD) cycles. The electronic structural properties explain density functional theory (DFT).