Efficiently\nDesigned Three-Dimensional Architecture\nof CoMn₂O₄ Decorated V₂CT_<i>x</i> MXene for Asymmetric Supercapacitors

Abstract

The structure, morphology, stoichiometry,\nand chemical characterization\nof the V₂CT_<i>x</i> MXene, CoMn₂O₄, and V₂C@CoMn₂O₄ nanocomposite, prepared by using a soft template method, have been\nstudied. The electron microscopy studies reveal that the V₂C@CoMn₂O₄ composite incorporates mesoporous\nspheres of CoMn₂O₄ within the 2D layered structure\nof MXene. The specific capacitance of the composite electrode is ∼570\nF g^–1 at 1 A g^–1, which is significantly\nhigher than that of the sum of the individual components. It also\nexhibits great rate capability and a Coulombic efficiency of ∼96.5%\nover 10000 cycles. An asymmetric supercapacitor prototype created\nwith V₂C@CoMn₂O₄//activated carbon\noutperformed other reported ASCs in terms of achieving a high energy\ndensity of 62 Wh kg^–1 at a power density of 440\nW kg^–1. The improved response of V₂C@CoMn₂O₄ and ASC is attributed to the enhanced active\narea available for charge transfer and the synergistic interaction\nbetween CoMn₂O₄ spherical particles and nanolayered\nMXene. Supporting density functional theory (DFT) calculations are\nperformed to understand the impact of composite heterojunction formation\non its detailed electronic structure. Our atomistic simulations reveal\nthat by incorporating CoMn₂O₄ in V₂C, the density of electronic states at the Fermi level increases,\nboosting the charge transfer characteristics. These modifications\nin turn enhance the charge storage capabilities of heterojunction.\nFinally, the merits of the V₂C@CoMn₂O₄ composite electrode are discussed by comparing it with those of\nother existing high-performance MXene-based composite electrodes.