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

Abstract

ZIF-derived N, S-codoped porous carbon dodecahedra are prepared and used as the high-performance cathode for aqueous ZHSC via a facile two-step doping strategy, which exhibit an ultra-long cycle life and a remarkable cycling stability with 97.1% capacity retention after 100,000 charge–discharge cycles (3960h). • N, S-PCD were synthesized by a facile two-step doping strategy. • DFT reveals that N and S dopants effectively boost the chemical adsorption of Zn 2+ . • Ex-situ SEM, XRD and XPS are applied to explore the working mechanism of N, S-PCD. • The assembled Zn//N, S-PCD device exhibits a long cycle life for 100,000 cycles. 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 Zn 2+ 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 Zn 2+ ions and improve the electronic conductivity, which synergistically enhance the Zn-ion storage performance.