2D porous layered NiFe2O4 by a facile hydrothermal method for asymmetric supercapacitor

2D porous layered NiFe2O4 nanostructures were successfully synthesized via a facile hydrothermal method and subsequent high-temperature calcination route. Benefiting from its advantages of the unique 2D porous layer nanostructures with large specific surface area (116.35 m2 g−1) and abundant mesoporosity, the as-prepared NiFe2O4 electrode displayed a high specific capacitance of 425.62 F g−1 at a current density of 1 A g−1, excellent capacitance retention rate of 75.26% at current density of 16 A g−1 compared with 1 A g−1, and long cycle life (88.61% of the maximum capacitance value after 3500 cycles) through the three-electrode system test. Moreover, an aqueous asymmetric supercapacitor based on the 2D porous layered NiFe2O4 as a positive electrode and the activated carbon as a negative electrode was assembled for the first time. The NiFe2O4//AC ASC device delivered a high specific capacitance of 105.94 F g−1 at a current density of 1 A g−1 in a voltage window of 1.6 V, and could achieve a high energy density of 37.67 Wh/kg, excellent rate capability, and good long-term cycling stability (84.21% retention after 4000 cycles). These results demonstrated that the as-fabricated 2D porous layered NiFe2O4 could be one of the promising electrode materials for asymmetric supercapacitors.