Biomass-Derived Porous Carbon-Anchoring MnFe2O4 Hollow Sphere and Needle-Like NiS for a Flexible All-Solid-State Asymmetric Supercapacitor

Flexible asymmetric supercapacitors fabricated by using biomass-derived carbon are sustainable candidates for manufacturing state-of-the-art energy storage devices for contemporary electronics. However, seeking suitable electrode materials for fabricating cathodes compatible with anodes is still a formidable challenge. Herein, a MnFe2O4–NiS–porous carbon nanocomposite was synthesized and utilized as the cathode electrode material and porous carbon, having a high surface area, was used as the anode electrode material for assembling a flexible all-solid-state asymmetric supercapacitor device. Due to the synergy between the MnFe2O4 and NiS, entrenched in a porous carbon network, the device exhibited a high power performance suitable to be used in portable electronic devices. The device manifested its capability of delivering a high energy density of 113 Wh kg–1 at a power density of 1500 W kg–1 with remarkable stabilization under 10 000 cycles, exhibiting 2% capacitance deterioration only. Also, the electrochemical performances of the fabricated device remained unimpaired even under harsh bending deformities owing to its stability and mechanical robustness. The current study encourages the development of metal oxides, transition metal chalcogenides, and porous carbon-based nanocomposites for flexible energy storage devices.