Synthesis And Electrochemical Properties Of Nickel/Cobalt/Zinc Based Electrode Materials

In recent years,nickel/cobalt/zinc based materials have been proved to be a sort of promising materials,especially in aspects of electrochemistry,catalyst etc.Specifically,nickel/cobalt/zinc based metal-organic materials have widespread applications in non-noble metal electro catalyst field;nickel-cobalt hydroxides are high performance pseudo-capacitive materials;nickel/cobalt/zinc based oxides are extensively used in new energy devices.It is known that the research area about nickel/cobalt/zinc based materials is attractive due to environment protection issue and outstanding properties of this kind of materials.While,quite a few challenges are to overcome about controlled morphology and crystal phase synthesis of nickel/cobalt/zinc based materials.Here,some novel ideas are proposed to overcome the challenges about controlled synthesis of nickel/cobalt/zinc based materials.Specific contents are as following:?1?Microsphere nickel/cobalt/zinc based metal-organic materials?Ni₁Co₂-g and ZniCo2-g?are prepared by solvothermal method and further possible microsphere formation mechanism is proposed.Besides,electro-catalytic tests prove that Zn₁Co₂-g350 sample is high performance OER catalyst and shows great application value in metal-air batteries.?2?By ion exchange method nickel cobalt hydroxides are easily obtained from nickel-cobalt organic precursors.Obtained nickel cobalt hydroxides' electrochemical performances are evaluated by CV PA,EIS,etc.It is proved that maximum specific capacitance of 1226.6 F/g?lA/g?is accessible when the nickel-cobalt ratio is 1:2.?3?A simple refluxing method is firstly developed for phase control synthesis of two-dimensional nickel-cobalt hydroxide.The control is briefly achieved by adjusting solvents with hexamethylene tetramine?HMT?serving as precipitant.Benefiting from phase control,two dimensional structure and synergistic effect of nickel-cobalt,the obtained a phase Ni-Co hydroxide?Ni-Co ratio 1:1?can deliver a significantly enhanced specific capacitance of 2366.6 F/g?1A/g?,which is almost 4.48 times higher than a-Co?OH?2 and 13.4 times higher than ?-Co?OH?2.In two electrode system,ultrahigh specific capacitance of 433.3 F/g?1A/g?can be obtained.Besides,the as-fabricated a-Co0.5Ni0.5 devices with activated carbon serving as positive electrodes demonstrated gravimetric energy density of 38.5 Wh/kg at the power density of 0.8 kW/kg and good cycling stability?4?Porous microsphere Co3O4,ZrnCo2O4 and NiCo₂O₄ are prepared from nickel/cobalt/zinc based metal-organic materials by annealing in air atmosphere.Furthermore,lithium ion battery tests are conducted to survey the performance of Co3O4,ZrnCo2O4 and NiCo₂O₄ anode materials.The discharge capacity of NiCo₂O₄ is 1304 mAh/g at a current density of 100 mA/g for the first cycle and can retain 450 mAh/g after 20 cycles at a current density of 150 mA/g.