The Preparation Of Supercapacitor Ni?OH?₂/NiO And The Research On Their Electrochemical Performances

Ni?OH?₂ and NiO have been widely used as active materials for energy storge and conversion devices,because these high theoretical specific capacitance,friendly environment,and rich source of raw materials.In recent years,these have been hot spot in the field of supercapacitor electrode materials.However,their actual capacity is far below the theoretical capacity,because of their unstable structure and low electrical conductivity.In this experiment,the hollow box-shaped Ni?OH?₂ and NiO were prepared by the template method.By composited graphene,the microstructure change and the improbement of the electrochemical performance in the alkaline electrolyte were studied.The prepared samples were characterized by X-ray powder diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,cyclic voltammetry?CV?,galvanostatic charge discharge?GCD?and Electrochemical impedance spectroscopy?EIS?.Hollow box-shaped Ni?OH?₂ nanoparticles were prepared by the template method.The prepared nanoparticles have a size of 200-300 nm and uniformly morphology.The electrochemical performances showed a specific capacitance of 717.84 F/g at 1 A/g,a retention of 6.6%from 1 A/g to 5 A/g,and a retention rate of 44.12%at 2 A/g in 2000cycles.The Ni?OH?₂/RGO composites were prepared by hydrothermal method.When Ni?OH?₂:GO?NG6?is 6:1,the results showed the best performance and the specific capacitance reaches 626.84F/g at 1A/g.The retention of the capacity from 1 A/g to 5 A/g is 50%,an increase of 43.4%,the retention at 2000 circles at 2 A/g is 69.1%,and the addition of graphene increases the cycle stability by 24.98%.Hollow box-like NiO was prepared by high-temperature calcination.The results showed that the hollow box-like structure did not change and the optimum sintering temperature was 450°C.Its performance is that the specific capacitance reaches 1188.6F/g at 1 A/g,which is higher than 717.84 F/g of Ni?OH?₂.The retention rate of the capacity from 1 A/g to 5 A/g was 88.6%,and the retention rate at 2000 cycles was 51.9%at 2 A/g.On the basis of the above,the composite?NiO/RGO?of nickel oxide and graphene was prepared by the method of physical mixed sintering.And by changing the proportion of raw materials to adjust the performance of composites,the results showed that when the ratio of NiO and GO is 2:1,the composite NiO/RGO exhibited the best electrochemical performance.And the specific capacitance reaches 670.8 F at 1 A/g.the retention ratio of the capacity from 1 A/g to 5 A/g was 69.8%,and the retention after the 2000 cycle was49.6%at 2 A/g.