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