NiSe ₂ Carbon Nanowires Encapsulated within Graphene Nanosheets for Applications as Asymmetric Supercapacitors

On account of the relatively low charge transfer capability, limited surface area, low energy density, and finite cycling life of supercapacitors, it is imperative to further explore and develop electrode materials for supercapacitors that exhibit higher specific capacitance, superior conductivity, and enhanced stability. Hence, a three-dimensional graphene-encapsulated coral-like nickel selenide carbon nanowire (3DG/NiSe 2 CNWs) hybrid aerogel was synthesized via a self-assembly and one-step selenization approach. The 3DG/NiSe 2 CNWs electrode delivered a high specific capacitance of 1318.4 F g –1 at a current density of 1 A g –1 . A high capacity retention of 91.34% was maintained after 9,000 cycles at a current density of 5 A g –1, underscoring its robust electrochemical stability. The as-fabricated 3DG/NiSe 2 CNWs//FeN-PCNS asymmetric supercapacitor exhibited excellent electrochemical performance, delivering an energy density of 34.04 Wh kg –1 at a power density of 800 W kg –1 . Moreover, it demonstrated outstanding cycling stability with a capacity retention of 86.29% after 5000 cycles.