Targeted design strategies for a highly activated carbon cloth cathode/anode to construct flexible and cuttable sodium Ion capacitors with an all-woven-structure†

Carbon cloth (CC) is a promising flexible substrate to construct flexible electrodes. However, commercial CC suffers from high price, large dead weight/volume and poor electrochemical activity, severely affecting the energy/power density of energy storage devices. Herein, both a porous CC (PCC) cathode and hard carbon CC (HCC) anode are rationally designed and prepared via targeted strategies using scalable and renewable cotton cloth. The full microporous structure of PCC ensures a complete self-supporting structure, large specific surface area and high performance based on PF₆⁻. The non-porous structure with localized graphitic nanodomains of HCC contributes efficient sodium storage comparable to that of a capacitor with better flexibility. Consequently, both the PCC cathode and HCC anode realize high reversible capacity, outstanding rate capability, and ultralong cycling life in the half/full cell of a sodium ion capacitor system. More significantly, a flexible all-cloth sodium ion capacitor is assembled using the PCC cathode, HCC anode and cotton cloth separator, which provides stable power output even under bending and cutting conditions owing to its all-woven-structure. In addition, the structural design strategy, structure–activity relationship, and charge/discharge mechanism of CC electrodes are studied in detail, providing a constructive view for developing low-cost CC-based electrodes with high energy storage activity.