Biomass derived anode for high-electrochemical performance potassium-ion capacitors

Low cost metal ion storage system with abundant resources and high working voltage is promising candidate for current market demand. Advance energy technologies are focusing on the development of energy storage system via waste management. Here flexible potassium-ion capacitor was developed using waste silk cocoon from textile industry as a carbon source for N-S doped carbon nanofibers. This carbon material used as an anode material for K+ ion excessive adsorption through potassium alloy on the N-S doped carbon nanofiber as anode and large graphitic layer containing exfoliated graphite cathode. The present anode exhibits high electroactive surface area and hierarchical mesoporous structure. High specific capacitance, cyclic stability and electrochemical rate stability exhibits by this anode due to its excellent mechanical stability and high conductivity. Keeping these features in mind, a potassium-ion capacitor was constructed using N-S doped carbon nanofibers as anode and exfoliated graphite with large graphitic layers as cathode electrodes. The capacitor displays a high specific capacitance 200 mAh g−1 and stable cycling life (68% capacity retention over 140 cycles). This will promote application of flexible N-S doped carbon nanofibers as hybrid capacitors. The satisfactory electrochemical results promote the waste management concept for scalable production of eco-friendly energy storage system.