Selenized Binary Transition Metals-MXene Composite for High-Performance Asymmetric Hybrid Capacitors.

The exploration of innovative and high-efficiency energy storage materials is crucial for advancing high-performance supercapacitors. In this study, a novel composite material is synthesized, comprising multilayered MXene (TiCT) nanoparticles integrated with porous NiCoSe nanosheets. The accordion-like nanostructure of MXene and its strong interfacial interactions enhance the surface area and cycling stability of the nanocomposite. Additionally, substituting selenium (Se) for Ni-Co-based hydroxides modulates orbital hybridization with the corresponding metal cations, significantly improving electrochemical activity and reducing the adsorption/desorption energy barrier for electrolyte ions. The synergistic interaction between these two materials enabled the composite electrode to achieve a high specific capacity of 796.25 C g at 1 A g while maintaining over 90% of its initial capacity after 8000 cycles. Furthermore, the as-fabricated asymmetric hybrid capacitor, employing activated carbon as the negative electrode, delivered an energy density of 64.36 Wh kg at a power density of 0.8 kW kg, surpassing the performance of most previously reported hybrid capacitors. The developed composite structure holds significant potential for integration into various electrochemical devices, such as batteries, sensors, and electrolyzers.