Preparation of N, B, and F co-doped porous carbon derived from corn husk biomass and its applications in flexible symmetric supercapacitors

• N, B, and F co-doped porous carbon derived from corn husks exhibit enhanced pseudocapacitive effects. • Optimized CHPC@NBF-2 delivers a high specific capacitance of 488.5 F g −1 at 0.5 A g −1 . • The device shows excellent electrochemical stability at different bending angles. • Series and parallel connection configurations broaden the application prospects of the device in energy storage. Green and renewable biomass-derived porous carbon materials fabricated via heteroatom doping can effectively improve the energy storage capacity of supercapacitors (SCs). Heteroatom doping can significantly enhance the electrochemical performance of electrode materials for SCs. In this work, waste corn husk was employed as a low-cost natural carbon source to synthesize N, B, and F co-doped corn husk-based porous carbon (CHPC@NBF), using NaCl as the template and KOH as the activator. The optimized CHPC@NBF-2 displays a specific surface area of 1076 m 2 g −1 , a high specific capacitance of 488.5 F g −1 at current density of 0.5 A g −1 , and retains a capacitance retention rate of 93.8 % after 10,000 cycles. The assembled CHPC@NBF-2//CHPC@NBF-2 device achieves a specific capacitance of 356.7 F g −1 , and an energy density of 39.4 Wh kg −1 in 1 M Na 2 SO 4 electrolyte. Furthermore, the flexible symmetric SCs based on PVA/KOH gel electrolytes exhibit a specific capacitance of 403.1 F g −1 within a stable voltage window of 0–1.3 V, along with a high energy density of 23.7 Wh kg −1 . The device also retains 92.3 % of its capacitance after 10,000 cycles. Therefore, multi-heteroatom co-doped corn husk porous carbon present a promising candidate for the rational design of advanced electrode materials toward high-performance energy storage devices.