Facile hydrothermal synthesis of flowerlike ZnCo2O4 microspheres as binder-free electrodes for supercapacitors

Flowerlike ZnCo2O4 microspheres were synthesized using Ni foam substrates by a facile hydrothermal method combining post-annealing treatments. The obtained microspheres are about 5 μm in diameter and composed of porous ultrathin nanosheets. And the supercapacitors based on these microspheres show a high specific capacitance (689.4 F/g at the current density of 1 A/g), good rate performance (336.6 F/g at 15 A/g), and excellent cyclic stability (97.1% capacitance retention after 1500 cycles at a high current density of 10 A/g). These remarkable electrochemical performances imply that the flowerlike ZnCo2O4 microspheres would have great potential applications in SCs.