Facile Fabrication of Three-Dimensional Hierarchical Nanoarchitectures of VO₂/Graphene@NiS₂ Hybrid Aerogel for High-Performance All-Solid-State Asymmetric Supercapacitors with Ultrahigh Energy Density

In this study, a hierarchical mesoporous VO 2 /graphene@NiS 2 hybrid aerogel is synthesized through the sol–gel and hydrothermal growth approaches. The resultant VO 2 /graphene@NiS 2 hybrid aerogel electrode offers a high specific capacitance up to 1280.0 F g –1 (142.22 mAh g –1 ) at a current density of 1 A g –1 and exhibits an outstanding cycling performance. The distinguished electrochemical performance of the VO 2 /graphene@NiS 2 electrode is attributable to the synergistic effect among VO 2 particles, graphene networks, and NiS 2 nanoflakes, which not only increases the specific surface area and conductivity but also gives extra pseudocapacitance to the VO 2 /graphene@NiS 2 hybrid aerogel electrode. In addition, a high-performance all-solid-state asymmetric supercapacitor (SC) is successfully assembled by using the novel 3D interconnected VO 2 /graphene@NiS 2 hybrid aerogel as the positive electrode, graphene aerogel as the negative electrode, and PVA/KOH gel as the electrolyte. The assembled VO 2 /graphene@NiS 2 hybrid aerogel//graphene aerogel device achieves a superior energy density of 60.2 Wh kg –1 at a power density of 350.0 W kg –1 and sustains 86.2% of its initial capacitance after 10000 charge/discharge cycles. These results reveal that the multiple composite of a VO 2 /graphene@NiS 2 hybrid aerogel is a promising candidate material for high-performance SCs in virtue of its high capacitance, conspicuous energy density, and long-term cycling stability.