Preparation And Electrochemical Properties Of Ni_1-xCo_x（OH）₂Supported On Nickel Foam

Spherical clusters of Ni（OH）₂nanosheets are directly grown on skeletons of nickelfoam via a facile template-free spontaneous growth method. The obtained electrode（β-Ni（OH）₂/Ni-foam） is characterized by X-ray diffractometry, scanning and transmissionelectron microscopy and thermal analysis. Results show that Ni（OH）₂has a β-phasestructure and presents on the nickel foam skeleton mostly as spherical clusters with adiameter of¹0μm. The spheres are composed of nanosheets with thickness of⁶0nm,width of²30nm and length up to²μm, and the nanosheets are assembled bynanoparticles with diameter of²0nm. The electrochemical performance of theβ-Ni（OH）₂/Ni-foam electrode is evaluated by cyclic voltammetry and galvanostaticcharge-discharge tests. The difference between the oxygen evolution reaction onsetpotential and the anodic peak potential for this electrode （¹00mV） is larger than that forβ-Ni（OH）₂nanosheets and nanotubes powder electrode （⁶5-77mV） and much larger thanthat for commercial spherical β-Ni（OH）₂powder electrode （²5-47mV）, indicating that theβ-Ni（OH）₂/Ni-foam electrode can be fully charged. The specific discharge capacity ofβ-Ni（OH）₂in the β-Ni（OH）₂/Ni-foam electrode reaches275mAh g^-1, which is close to thetheoretical value, lower than that of β-Ni（OH）₂nanotubes (315mAh g^-1), but higher thanthat of nanosheets (219.5mAh g^-1), commercial micrometer grade spherical powders (265mAh g^-1) and microtubes (232.4mAh Fg^-1).The nano-scale β-Ni（OH）₂doped with Co electrode (Ni_1-xCo_x（OH）₂) was manufacturedthrough the same method, and its structur and morphology were characterized by XRD andSEM The results indicated that the material doped with Co is still nano-seale β-Ni（OH）₂,but the crystallinity and shape changed a lot.The electrochemical performances indicatedthat: The material doped with10%Co exhibited good performances, The specific dischargecapacity reaches279.9mAh g^-1, when the discharge specific capacity is1C, eenhanced by12%. And the charge transfer resistance was reduced from0.24to0.06because of theaddition of Co.The nano-scale β-Ni（OH）₂with different morphology was also prepared.They wereprepared from different nickel salt.It was found that:The different anionics betweenβ-Ni（OH）₂layers could reduce the charge transfer resistance of the nickel electrode reaction, improved protons conductivity. The specific capacity, cycling life and the dischargingplateau of the material prepared from NiSO₄were superior to others. The minimum grainsize is16.57nm, the specific capacity is243mAh g^-1, circulation efficiency is88.9%,after100cycle capacity up to229mAh g^-1, attenuation to83.6%, circle life is stability.