Hierarchically porous N-doped carbon framework with enlarged interlayer spacing as dual-carbon electrodes for potassium ion hybrid capacitors

Abstract Thanks to the high power/energy densities together with lower cost, potassium ion hybrid capacitors (PIHCs) have broad application prospects. Nevertheless, the significant volume changes during K+ intercalation/deintercalation together with the misfit between anode as well as cathode limit their further development. Herein, hierarchically porous nitrogen-doped carbon (N-HPC) is fabricated and used as two electrodes materials for PIHCs. The three-dimensional hierarchical porous structure and large interlayer distance of N-HPC afford enough space to alleviate the volume expansion of potassium. Furthermore, the suitable N doping enables additional active sites towards K+ storage and improves electrical conductivity of electrodes. Hence, the constructed PIHCs assembled with dual N-HPC electrodes deliver a high energy density of 103.5 Wh kg‒1 at 1000.0 W kg‒1. Meanwhile, the PIHCs devices also display superior cycling stability, achieving a capacity retention rate of 70.2% after 10,000 cycles at 1.0 A g‒1. Graphical Abstract Hierarchically porous nitrogen-doped carbon (N-HPC) is fabricated and used as two electrode materials for PIHCs. The three-dimensional porous structure of N-HPC, the larger inter-layer distance, and the synergy of N-doped introduction of more active sites make it have good magnification properties. At the same time, the assembled PIHCs cycle of 10000 laps has an excellent cycle retention rate.