Hydroxyl-riched halloysite clay nanotubes serving as substrate of NiO nanosheets for high-performance supercapacitor

Despite the great progress in NiO-based materials for supercapacitors in recent years, the tested specific capacitance of NiO-based materials is usually much lower than its theoretical specific capacitance. Here, a novel hierarchical nickel oxide@halloysite nanocomposite has been synthesized via a simple precipitation reaction. In the resulting structure, halloysite tubes with abundant hydroxyl group are closely assembled with ultrathin and standing NiO nanoflakes. This architecture designed is expected to enrich accessible electroactive sites, faster kinetics of NiO/NiOOH redox pair, as well as enhance participation degree of NiO during the charging/discharging process. As a result, the as-prepared NiO@halloysite nanocomposite exhibits excellent electrochemical properties in terms of high charge storage capacitance (1047.3 F g^-1 at 5 A g^-1), high rate capability and stable cycling performance (1338 F g^-1 after 7200 cycles at a current of 10 A g^-1).