Nanoflower-like NiCo2O4 grown on biomass carbon coated nickel foam for asymmetric supercapacitor.

Nanoflower-like NiCo 2 O 4 is grown directly on a three-dimensional gelatin-based carbon–nickel foam (GCNF), which is prepared by a facile hydrothermal strategy with annealing treatment. The as-synthesized binder-free NiCo 2 O 4 /GCNF composites are used for high-performance supercapacitors. The binder-free design can avoid the "dead surface" caused by binders and additives in traditional electrodes, thus achieving more efficient charge and mass exchange, leading to improved conductivity of electrodes. Furthermore, the proposed design provides a wider interface area and abundant active sites, which significantly improve the electrochemical capacitance performance. The electrode has a high specific capacitance of 1416 F g−1 at a current density of 1 A g−1, and excellent cycling performance. An asymmetric supercapacitor (ASC) was assembled with the structure NiCo 2 O 4 /GCNF//activated carbon and a maximum voltage of 1.5 V delivers a high energy density of 48.6 W h kg−1 at a power density of 749.3 W kg−1. Moreover, the ASC shows good cycling performance with 88.5% capacitance retention after 10,000 cycles at a high rate of 5 A g−1. Image 1 • Nanoflower-like NiCo 2 O 4 was grown on a 3D gelatin-based carbon–nickel foam. • Edible gelatin as a carbon source and contributes to the capacitance of electrode. • The NiCo 2 O 4 /GCNF composites were used as binder-free electrodes for supercapacitors. • The assembled asymmetric supercapacitor exhibits good electrochemical performance. [ABSTRACT FROM AUTHOR]