Chitosan-based high-performance flexible supercapacitor via "in-situ co-doping/self-regulation-activation" strategy

The construction of N, P co-doped hierarchically porous carbons (NPHPC) by a facile and green approach is crucial for high-performance energy storage but still an enormous challenge. Herein, an environment-friendly "in-situ co-doping, self-regulation-activation" strategy is presented to one-pot synthesize NPHPC using a phytic acid-induced polyethyleneimine/chitosan gel (PEI-PA-CS) as single precursor. NPHPC displayed a specific surface area of up to 1494 m² g^-1, high specific capacitance of 449 F g^-1 at 1 A g^-1, outstanding rate capability and cycling durability in a wide temperature range (-20 to 60 °C). NPHPC and PEI-PA-CS electrolyte assembled symmetric quasi-solid-state flexible supercapacitor presents superb energy outputs of 27.06 Wh kg^-1 at power density of 225 W kg^-1. For capacitive deionization (CDI), NPHPC also exhibit an excellent salt adsorption capacity of 16.54 mg g^-1 in 500 mg L^-1 NaCl solution at a voltage of 1.4 V, and regeneration performance. This study provides a valuable reference for the rational design and synthesis of novel biomass-derived energy-storage materials by integrating phytic acid induced heteroatom doping and pore engineering.