Preparation, Characterization And Supercapacitance Of Nickel Cobalt Sulphide-based Electrode Materials

Compound of a transition metal elements and elemental sulfur is formed with a unique nano-structural and electrical properties, so people had a great appeal for its application in the energy storage device. Metal sulfide has special physical and chemical properties, its application such as the direction of lithium ion batteries, solar controller, the catalyst as well as superconductors have great potential. Sulphides specific capacitance is much larger than carbon-based material, while its use lower cost. In terms of electrical conductivity, a metal sulfide should be much higher than the polymer. A simple solvothermal synthesis of the electrode material prepared hollow micro-nano structure of nickel and cobalt-based metal sulfide in this paper.The detailed research contents of the thesis were described as follows:?1? The Ni₇S₆/Co₃S₄ nanoboxs with hollow mesoporous have been preparationed by a two-step solvothermal method, and analyzing the energy storage mechanism of Ni₇S₆/Co₃S₄ heterogeneous structure. Unlike traditional storage mechanism, we propose a new energy storage mechanism. Simultaneously, for the existence of mesoporous, it can also improve the specific surface area, while synergies between heterogeneous component structure, can promote the electrochemical reaction,thereby improving performance. Its electrochemical data demonstrated that electrode has a capacitance of 677 F/g at 4 A/g, and even remains 64% at large current density of 10 A/g. More remakably, assembled the asymmetric device with carbon material.Through another five thousand times cycle at 3A/g, it was still maintain 86%,indicating its desirable electrochemical stability.?2? The binary metallic sulfide NiCo₂S₄ electrode materials by changing the experimental conditions have been developed. The efficient electrochemical reaction was depending on binary metallic elements enhance the conductivity of the material and hollow mesoporous structure effectively increases area. The data reveal that current density from 4 A/g to 10 A/g, the specific capacity still keep 61.8%, indicate NiCo₂S₄ electrode material still have a high capacitance. We assembled the asymmetric device with carbon material, the entire capacitor capacitance was 82 F/g when at 0.2 A/g. The entire capacitor largest energy and power were 25.6 Wh/kg and2250 W/kg.?3? The hollow NiCo₂S₄/Co₉S₈ ellipsoid composite electrode material via solvothermal method have been developed. And by changing the content of NH₄HCO₃, and probe the effect of NH₄HCO₃ on morphology and composition of the electrode material. The as-synthesized NiCo₂S₄/Co₉S₈ electrode material exhibits excellent performance, its capacitance was 749 F/g when at 4 A/g. And even remains64 % at 10 A/g. We assembled the asymmetric device with carbon material, the entire capacitor mass capacitance was 107 F/g when at 0.25 A/g. Its largest energy and power were 33.5 Wh/kg and 3750 W/kg. The SC through another five thousand times cycle at 3 A/g was still maintain 86%, indicating its desirable electrochemical stability.This hollow structure material improved the useful area, NiCo₂S₄ and Co₉S₈ two phases has a wealth of heterogeneous structure, in addition, synergism was happened between the two phases, all above was in favor of function, and ultimately exhibits excellent electrochemical performance.