Tetra-heteroatom self-doped and hierarchical porous carbon toward high-performance zinc-ion hybrid supercapacitors

Porous carbon has been reported as a promising cathode material for zinc-ion hybrid supercapacitors (ZHSCs). However, it is limited by inferior ionic diffusion and insufficient active adsorption sites during charge/discharge process. Herein, a tetra-heteroatom self-doped and hierarchical porous carbon material (PMAC700-3) derived from paper mulberry has been fabricated through facile carbonization and activation process. Owing to the high tetra-heteroatom content (similar to 15.76 % atomic ratio of N, O, S, P), hierarchical porous structure, and specific surface area (1736.1 m(2) g(-1)), the PMAC700-3 cathode exhibits considerable ionic diffusion, abundant active adsorption sites, and superior electric conductivity, thereby significantly improving the electrochemical performance of ZHSCs. The ZHSC based on PMAC700-3 cathode delivers an excellent specific capacitance of 240.7 F g(-1) at 0.5 A/g, energy density of 108.3 Wh kg(-1), power density of 450 W kg(-1), along with exceptional cycling stability (97.7 % capacity retention after 10,000 cycles at 10 A/g). Under high mass loading of 39.09 mg cm(-2), the areal capacitance of PMAC700-3 based ZHSC reaches up to 4.26 F cm(-2). This work provides a universal strategy to achieve multiple heteroatoms self-doped porous carbon materials from biomass for ZHSCs.