Graphene-wrapped (Ni,Co)Se2 carbon nanowires toward high performance hybrid supercapacitors

To probe the next generation of flexible supercapacitors for practical application, small size, excellent electrical conductivity, low cost, Eco-friendly and excellent capacitance are prerequisites. However, due to dissatisfied electrical conductivity, limited surface area and low porosity, which results in few active sites and long ion transport channels, electrochemical improvements are needed for bimetallic selenide-based flexible supercapacitors. Hence, novel three dimensional graphene (3DG) encapsulated cobalt-nickel selenide carbon nanowires [3DG/(Co,Ni)Se2 CNWs] composite aerogels was successfully fabricated through a modified self-templating approach. The assembled 3DG/(Co,Ni)Se2 CNWs electrode showcases outstanding electrochemical performance, achieving a high specific capacitance of 1286 F g-1 at 1 A g-1 attributed to its combination structure of carbon based materials and nanowires. It demonstrates excellent cycling stability, with a capacity retention of 88% after 3000 cycles at 2 A g-1. The prepared 3DG/(Co,Ni)Se2 CNWs//active carbon (AC) asymmetric flexible all-solid-state supercapacitors demonstrates outstanding electrochemical properties, achieving an energy density of up to 28 Wh kg-1 at a power density of 800 W kg-1. Even after 6000 cycles at 5 A g-1, it retains 84.15% of its specific capacitance, thus presenting a new direction for energy storage applications.