Silver particle-loaded nickel oxide nanosheet arrays on nickel foam as advanced binder-free electrodes for aqueous asymmetric supercapacitors

Conductive metal loading is an efficient approach for enhancing the electric conductivity of redox-active transition-metal oxide electrodes. In this study, Ag particle-loaded NiO/nickel foam (Ag-NiO/NF) composites were fabricated using a green chemistry method. The anchored Ag particles standing on the surface of NiO nanosheet arrays helped improve the electrical conductivity and were thus beneficial for supercapacitors (SCs). The as-developed Ag-NiO/NF electrode delivered a specific capacitance of 1254.9 F g−1 at the current density of 1 A g−1, which is higher than that of NiO/NF electrode (946.3 F g−1). Using such Ag-NiO/NF as a positive electrode, we further fabricated aqueous asymmetric SC devices with reduced graphene oxide as a negative electrode. Owing to the efficient electron transport and short ion diffusion paths in the designed electrode, the devices exhibited a high specific capacitance of 97.9 F g at 1 A g−1 with a high energy density of 26.7 W h kg−1 at a power density of 1017.1 W kg−1 and great cyclic stability.