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 VO2/graphene@NiS2 hybrid aerogel is synthesized through the sol–gel and hydrothermal growth approaches. The resultant VO2/graphene@NiS2 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 VO2/graphene@NiS2 electrode is attributable to the synergistic effect among VO2 particles, graphene networks, and NiS2 nanoflakes, which not only increases the specific surface area and conductivity but also gives extra pseudocapacitance to the VO2/graphene@NiS2 hybrid aerogel electrode. In addition, a high-performance all-solid-state asymmetric supercapacitor (SC) is successfully assembled by using the novel 3D interconnected VO2/graphene@NiS2 hybrid aerogel as the positive electrode, graphene aerogel as the negative electrode, and PVA/KOH gel as the electrolyte. The assembled VO2/graphene@NiS2 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 VO2/graphene@NiS2 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.