ZnCl2 induced hierarchical porous carbon for zinc-ion hybrid supercapacitors

Carbon-based cathode materials are highly desired for zinc-ion hybrid supercapacitors (ZHSs) due to their rich sources and low production cost. Here, a ZnCl2 induced hierarchical porous carbon is developed from corncob cellulose by a single-step activation process. The suitable micropores are conducive to the adsorption/desorption of zinc ions for the high energy storage, whereas the sufficient mesopores are in favor of the rapid migration of electrolyte ions for the high-rate performance, both which can effectively improve the performance of ZHSs. The ZHS fabricated with the optimized hierarchical porous carbon (ZnHPC-0.5) exhibits a high specific capacity of 120.3 mAh g−1 and a high energy density of 103.2 Wh kg−1. After 10000 cycles at a high current density of 5 A g−1, the capacity retention is 99.2%. In addition, the assembled quasi-solid-state flexible hybrid supercapacitor (QSSF-ZHS) also shows high specific capacities, satisfactory mechanical properties, and good application prospects.