Preparation of Manganese Cobalt-Based Binary Metal Oxide for High-Performance Quasi-Solid-State Supercapacitors

Supercapacitor electrode materials have extensively adopted manganese-based oxides, owing to their broad availability, environmentally benign nature, and abundant valence state composition. However, the issues of instability and poor electrical conductivity necessitate a search for modification strategies to improve their electrochemical behavior. Cobalt-doped Manganese-based binary metal oxides (MCOs) are synthesized via a straightforward hydrothermal process in this article. The optimal sample with doping ratio of 1:2 (MCO-2) exhibits remarkable rate performance in a supercapacitor configuration as an electrode, achieving specific capacitances of 4.48 and 3.90 F cm–2 at 10 and 50 mA cm–2, respectively. It retains up to 87.1% of its capacitance under high current density. Besides, a quasi-solid-state asymmetric device was constructed, utilizing the prepared MCO-2 oxide as the positive electrode and camphor seed-derived activated carbon (CSDC) as the negative terminal. The MCO-2//CSDC device demonstrates exceptional supercapacitive properties, with a remarkable areal capacitance of 238 mF cm–2, a noteworthy rate capability of 85.6% at 7 mA cm–2, and 85.0% capacity retention after 4000 cycles. Intriguingly, there are almost no difference in electrochemical performance before and after folding, demonstrating its excellent foldable properties. Such a straightforward technique can offer helpful direction for creating high-performance quasi-solid-state supercapacitor electrode materials.