Wearable superhigh energy density supercapacitors using a hierarchical ternary metal selenide composite of CoNiSe2 microspheres decorated with CoFe2Se4 nanorods

A rational and multicomponent design of hierarchical CoFe2Se4 (CFS) nanorods adhered to CoNiSe2 (CNS) microsphere composites is prepared for the first time via facile and eco-friendly synthesis methods. The hierarchical CFS–CNS robust architectures enhance the specific surface area and porosity and also increase the availability of electrochemically active sites, which provides ideal pathways for electrolyte diffusion and facilitates electron transportation. As a result, the as-prepared fabric-based CFS–CNS electrode delivers a maximum specific capacity of 183.4 mA h g−1 at a current density of 1 A g−1, with an excellent rate capability of 172.4 mA h g−1 at 8 A g−1 and outstanding cycling stability with 99.2% retention over 3000 cycles in aqueous 3 M KOH electrolyte solution. Moreover, the assembled fabric-based CFS–CNS//CFS–CNS symmetric SC achieves a high energy density of 80.2 W h kg−1 at 1000 W kg−1 and delivers an exceptional cycling stability with 97.02% retention over 3000 cycles as well as exhibiting excellent flexibility to sustain various deformations including bending and twisting. Utilizing the outstanding energy storage performance, the symmetric SC can light up a light-emitting diode for real-time applications.