A Ni1-xZnxS/Ni foam composite electrode with multi-layers: one-step synthesis and high supercapacitor performance

Multi-layer NixZn1-xS/Ni foam composites were synthesized by the facile method of a one-step hydrothermal reaction on a frame of Ni foam. The Zn element plays a critical role in constructing the multi-layer nanostructure. In particular, various layers with different morphologies work with good synergistic effect to provide an excellent electrochemical performance. The as-synthesized Ni1-xZnxS/Ni foam-2 h electrode shows a high specific capacitance (1815 F g(-1) at 1 A g(-1)) and outstanding rate properties (1050 F g(-1) at 100 A g(-1) and 50.1% rate retention over 200 A g(-1)). Moreover, a two-electrode Ni1-xZnxS/Ni foam-2 h//active carbon-graphene (AC-G) asymmetric supercapacitor device was fabricated and it delivers both a high specific energy density and an excellent cycling stability. The strategy presented here for constructing multi-layer structures is facile and effective, and could be expanded as a general method.