Reagent-assisted hydrothermal synthesis of NiCo2O4 nanomaterials as electrodes for high-performance asymmetric supercapacitors

In this study, mesoporous nickel cobaltate (NiCo2O4) nanomaterials were loaded onto nickel foam through a simple and environment-friendly reagent assisted hydrothermal method. The impacts of reagents on the micro-morphology and electrochemical capacitive properties were studied. The NiCo2O4 nanoneedle arrays prepared with cetyltrimethylammonium bromide (CTAB) as the auxiliary reagent exhibited a relatively higher specific surface area, convenient charge transport channel, excellent specific capacitance (1153.2 F g(-1) at a current density of 1 A g(-1)), remarkable rate performance (10 A g(-1), 812 F g(-1)) and good cycling stability (75% of the initial value is retained at 10 A g(-1) after 1000 cycles). The asymmetric supercapacitor assembled by the optimized NiCo2O4 nanomaterial as the positive electrode and activated carbon as the negative electrode provides an energy density of 22.5 W h kg(-1) at 800 W kg(-1), and displays an excellent cycle performance of 97.1% after 1000 cycles at 1 A g(-1). It is suggested that the CTAB-assisted nanoneedle array-structured NiCo2O4 electrode material could be a potential candidate for supercapacitors.