Construction\nof Cationic Vacancy-Rich Mulberry-Like\nMnCo<sub>2</sub>O<sub>4.5</sub> Nanostructures with High Surface Area\nfor High-Performance Hybrid Supercapacitors

Incorporating\ncationic vacancies into high surface area mesoporous\nstructured materials is a viable strategy for improving the electrochemical\nperformance of electrochemical energy storage/conversion devices.\nWe successfully developed a mesoporous mulberry-like MnCo<sub>2</sub>O<sub>4.5</sub> (MCO–DMF) with cation metal vacancies via\na solvothermal route using dimethylformamide (DMF) as the solvent.\nThe large surface area of the mulberry-like morphology offers numerous\nelectroactive sites and a high permeation of electrolyte ions, giving\nrise to an excellent electrochemical performance. For comparison,\nspheres like MnCo<sub>2</sub>O<sub>4.5</sub> (MCO-IPA) were prepared\nwithout cationic vacancies using isopropyl alcohol (IPA) as a solvent.\nThe cationic vacancies (Mn) in MCO–DMF were identified by employing\nvarious analytical techniques such as energy-dispersive X-ray spectroscopy,\nscanning and transmission electron microscopy, and X-ray photoelectron\nspectroscopy. The cation vacancies accelerated the charge transfer\nkinetics over the electrode–electrolyte interface in MCO–DMF\nwith abundant electroactive sites. In the backdrop of supercapacitor\napplication, the MCO–DMF electrode established a high specific\ncapacity of 628.2 C g<sup>–1</sup> at 0.75 A g<sup>–1</sup> than the MCO-IPA electrode (380.6 C g<sup>–1</sup>) with a greater cycling performance of 95.1% retention\nat 5 A g<sup>–1</sup> after 10,000 cycles. The MCO–DMF||AC\nhybrid supercapacitor (HSC) device exhibited a specific capacity of\n165.5 C g<sup>–1</sup> at 0.75 A g<sup>–1</sup> within a potential window of 0.0–1.5 V. The HSC device also\nhas a noteworthy energy and power densities of 58.5 Wh kg<sup>–1</sup> and 1026.7 W kg<sup>–1</sup>, respectively,\nwith a remarkable cycle stability of 91.4% capacity retention after\n10,000 cycles.