Two-step nitrogen and sulfur doping in porous carbon dodecahedra for Zn-ion hybrid supercapacitors with long term stability

Abstract Aqueous Zn-ion hybrid supercapacitors (ZHSCs) are promising energy storage devices for their intrinsic advantages of high theoretical capacity, low-cost, and intrinsic safety. However, due to the lack of efficient cathode materials for reversible insertion/extraction of Zn2+ ions, it remains a pivotal challenge to high cycling-stability ZHSCs. Herein, we report a facile two-step doping strategy to synthesize zeolitic imidazolate framework (ZIF)-derived N, S-codoped porous carbon dodecahedra (N, S-PCD), using as the high-performance cathode for ultralong-life aqueous ZHSC. Integrating the hierarchical porous architecture and N, S dual-doping, the as-assembled Zn//N, S-PCD ZHSC delivers a specific capacity of 133.4 mA h g-1 (300.2 F g-1) at 0.2 A g-1, and maximum energy density of 106.7 W h kg-1 at the power density of 160 W kg-1. Moreover, an ultra-long cycle life has been achieved with the device, retaining 97.1% capacity after 100,000 charge-discharge cycles (∼3960 h), which is the maximum life span for ZHSCs to date. Mechanism studies reveal that thes dual-doping of N and S could effectively boost the chemical adsorption of Zn2+ ions and improve the electronic conductivity, which synergistically enhance the Zn-ion storage performance.