Glutinous rice-derived carbon material for high-performance zinc-ion hybrid supercapacitors

The increasing demand for wearable electronic systems has driven research on portable electrochemical energy storage devices. Zinc-ion hybrid capacitors have recently received considerable attention owing to their benefits of environmental friendliness, safety, and low cost. However, their moderate energy density has severely hampered their use in portable electronic equipment. In this study, we used the sweet messes from glutinous rice alcoholic fermentation as a highly available green carbon source to prepare a new biomass-derived porous carbon material by mixing it with KOH under a nitrogen atmosphere. GRPC-A13 has a rich microporous structure, high micropore area (1991 m2 g−1), and abundant oxygen content (7.0 at.%). Subsequently, a carbon-based zinc-ion hybrid supercapacitor was assembled with GRPC-A13 as the cathode, and zinc foil and 2 mol/L ZnSO4 as the anode and electrolyte, respectively. Zn//GRPC-A13 devices offer an ultrahigh energy density of 116 Wh kg−1 at a power density of 800 W kg−1. In addition, they have a long lifetime of 270,000 constant-current charge/discharge cycles and still maintain 100 % Coulombic efficiency. This improvement is principally due to the rapid ion adsorption/desorption on the GRPC-A13 cathode electrodes and reversible zinc-ion plating/exfoliation on battery-type zinc negative electrodes. These results provide insight into the development of zinc-ion hybrid supercapacitors in miniature electronics.