| Electrochemical supercapacitors with higher power density,faster charge-discharge rate and longer cycle life have attached growing research interests for various applications,which can substitute for the fossil fuel energy as a rechargeable and environmentally friendly energy storage device.Developing high performance of energy storage device is dependent on the preparation of excellent design of electrode materials and the assembly of electrode.The pseudocapacitors for transition hydroxide-based nanomaterials with remarkable theoretical capacitances are chosen as the alternative electrode materials.Among the investigated transition metal oxide or hydroxide-based nanomaterials,nickel-based compounds such as Ni?OH?2 have attracted a large amount of attention due to their low toxicity,low cost and excellent electrochemical properties.However,other related studies mentioned that the rate capability and cycling stability of Ni?OH?2 was compromised due to the poor conductivity and the faradic redox reactions of Ni?OH?2.In this paper,Ni?OH?2 with different sizes have been synthesized through simple hydrothermal method.At the same time a novel electrode was made through dispersing Ni?OH?2 sheets onto the multilayer nickel foams.This system gave a great improvement in the capacitance,the rate capability and the cycle life of Ni?OH?2 sheets.The main content of this paper is as follows:1.Ultrafine ?-Ni?OH?2 nanosheets with an average diameter of about 14.5 nm have been fabricated by immersing Na?HCO3?2 nanoparticles into 6 M KOH solution.Two electrodes were prepared using the traditional and new method with the prepared nickel hydroxide nanoparticles as the electrode materials,named N1 and N3,respectively.The results demonstrated that the specific capacitance of N1 and N3 electrodes were 482.9 and 524.5C g-1 at 5 A g-1,respectively.And the specific capacitance of N1 and N3 electrodes retained 59.1 % and 83.8 % after 1000 cycles.It is obvious that the new method improved the electrochemical properties of ?-Ni?OH?2 nanosheets.The function and mechanism of the multilayer nickel foam system were discussed in detail.2.Ni?OH?2 sheets with an average diameter of about 150 nm have been fabricated using NiCl2·6H2O and Na2CO3.Two electrodes were prepared using the traditional and new method with the prepared nickel hydroxide sheets as the electrode materials,named A1 and A3,respectively.The specific capacitance of A1 and A3 electrodes retained 42 % and 80 % after 1000 cycles.It is obvious that the new method improved the electrochemical properties of Ni?OH?2 sheets.The function and mechanism of the multilayer nickel foam system were verified. |
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