Hierarchical Porous Doped Carbon Plates Derived from Chitosan Aerogel as Cathode for High Performance Zn‐ion Hybrid Capacitor

Abstract Zn‐ion hybrid capacitors (ZHCs), combined with features of rechargeable batteries and double‐layer supercapacitors, are considered as one of the most promising energy storage devices due to their high energy and power density. However, there are still many challenges in developing ideal carbon cathode to match the high capacity of Zn anode. In this work, an activated carbon aerogel (ACA) with hierarchical porous structure is successfully prepared via freeze‐drying, carbonization and KOH activation process. Thanks to the high accessible specific surface area, rational pore size distribution and N, O co‐doping, the as‐assembled ZHC based on the optimal sample exhibits high capacity of 299.5 F g −1 (133.1 mAh g −1 ) at 0.1 A g −1 , excellent rate capability of 57.6 % capacity retention even at 20‐fold higher current, together with good cycling stability (86.3 % capacity retention after 10000 cycles at 2 A g −1 ). More gratifyingly, it also displays impressive energy density of 106.5 Wh kg −1 , satisfactory power density of 3108 W kg −1 , and promising potential for practical applications. Based on our results, the ACA could be one of the promising candidates for carbon cathodes for ZHCs.