Polypyrrole nanoparticles embedded nitrogen-doped graphene composites as novel cathode for long life cycles and high-power zinc-ion hybrid supercapacitors

The well-designed network structure of synthetic polypyrrole (PPy) nanoparticles embedded on a nitrogen-doped graphene (N-rGO) surface was utilized as a cathode for aqueous zinc-ion hybrid supercapacitors. Owing to the combination of the redox surface of PPy and the two-dimensional network structure of N-rGO, the PPy/N-rGO cathode affords rapid transport channels for Zn2+ ion adsorption/desorption and a faradaic reaction toward the synergistic composite materials. Subsequently, the constructed zinc-ion hybrid supercapacitors with the optimized PPy/N-rGO cathode composites deliver the highest capacity of 145.32 mA h g-1 at 0.1 A g-1 and the maximum energy density of 232.50 W h kg-1 at a power density of 160 W kg-1. Besides this, excellent cycling stability of 85% retention after 10 000 charge-discharge cycles at 7.0 A g-1 was achieved. The high-rate capabilities with long life cycle performance of these novel zinc-ion hybrid supercapacitors could find practical use in a wide range of applications, ranging from next-generation electronic devices to large-scale stationary energy storage.