One-pot synthesis Ni-Cu sulfide on Ni foam with novel three-dimensional prisms/spheres hierarchical structure for high-performance supercapacitors

Abstract

Ni-Cu-S/Ni foam (NCSN) composite with prisms/spheres hierarchical structure was synthesized on Ni foam substrate via a facile one-pot hydrothermal method. The structural and morphological features of as-synthesized composites were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), and the cyclic voltammetry and galvanostatic charge-discharge tests were used to investigate the electrochemical properties of composites. By adding copper ions to the original nickel sulfide, a unique nanostructure with diverse morphology and strong synergistic effect among components was constructed, which possesses increased active reaction sites, effective charge transfer and stable hierarchical structure for cycling. In particular, the NCSN-6h electrode exhibits an improved areal capacitance of 2.135 F cm−2 at 1 mA cm−2 and higher than those of all the other NCSN samples with different hydrothermal reaction time and the corresponding single nickel sulfide sample without doped-copper ions (pure-6h). Typically, it delivers excellent rate property with an areal capacitance reaching 1.625 F cm−2 even at 50 mA cm−2 and good cycling stability (72.2% capacitance retention at a large current density of 50 mA cm−2 after 10000 cycles). The superior electrochemical capacity demonstrates that the NCSN should be a promising candidate for high-performance supercapacitor applications.