Enhanced cycle stability of a NiCo(2)S(4) nanostructured electrode for supercapacitors fabricated by the alternate-dip-coating method

Nanostructured nickel cobalt sulfide (NiCo(2)S(4)) electrodes are successfully fabricated using a simple alternate-dip-coating method. The process involves dipping a TiO(2) nanoparticles-covered substrate in a nickel/cobalt precursor solution and sulfur precursor solution alternately at room temperature. The fabricated bimetallic sulfide electrode exhibits a synergetic improvement compensating for the disadvantages of the two single metal sulfide electrodes, i.e. the poor cycle stability of the nickel sulfide electrode and the low specific capacitance (C(sp)) of the cobalt sulfide electrode. The two capacitive properties are optimized by adjusting the ratio of nickel and cobalt concentrations in the metal precursor solution, reaching a C(sp) of 516 F g(−1) at a current density of 1 mA cm(−2), with its retention being 99.9% even after 2000 galvanostatic charge–discharge cycles.