Rational Design of\nAsymmetric Spinel/Defect Spinel\n(ZnMn<sub>2</sub>O<sub>4</sub>/Cu<sub>1.5</sub>Mn<sub>1.5</sub>O<sub>4</sub>) Nanocomposite-Based Supercapacitor Devices for Efficient\nE

The increasing global demand for energy solutions has\ncreated the\nnecessity for innovative nanocomposite materials for efficient energy\nstorage applications. This urgency is driving significant advancements\nin energy storage technologies, raising hope for the future of energy\nsectors. Supercapacitors (SCs), high-performance electrochemical\nstorage devices, have earned considerable attention to address these\nchallenges. In this article, we have demonstrated a cost-effective,\neasily obtainable trimetallic spinel/defect-spinel oxide ZnMn<sub>2</sub>O<sub>4</sub>/Cu<sub>1.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> (ZMO/CMO) nanocomposite through a facile one-step solvothermal synthesis\nprocess. This nanocomposite demonstrated exceptional charge storage\ncapabilities. The charge storage mechanism was established by using\nDunn’s method, which reveals the diffusive nature of the electrode\nmaterial. The ZMO/CMO nanocomposite exhibits an impressive specific\ncapacitance of 468.1 F/g at 0.5 A/g, with 84% capacity retention even\nafter 20000 cycles, which was attributed to the oxygen vacancies within\nthe defect spinel structure. Moreover, we fabricated an asymmetric\ndevice utilizing ZMO/CMO as the cathode and activated carbon (AC)\nas the anode. This device attained an energy density of 48.1Wh/kg\nand a power density of 700 W/kg with excellent cycling stability,\nas mentioned before. Furthermore, our study featured its ability to\npower a standard LED light.