Study On Electrochemical And Mechanical Properties Of NiO Microflowers Electrode For Supercapacitor

With the rapid development of our society,the demand for energy has risen sharply,the non-renewable fossil fuels are drying up increasingly,and with it a series of environmental and pollution problems to be solved urgently have arisen,a lot of researchers have turned the target to the energy storage device which can realize the storage and energy conversion of the renewable new energy.Supercapacitors have high power density,excellent stability,fast charge�discharge rates and other advantages,have been widely used in the field of electric vehicles,solar power generation,aeronautics and astronautics,electronic communications and war industry and so on.The electrode material which plays a key role in the performance of supercapacitors has become a research hotspot in the field.Ni O microflowers and NiO&C composite microflowers electrode materials were prepared in this paper.The morphology,structure,electrochemical property and mechanical behavior of the prepared electrode materials were tested,and the electrochemical stability of the prepared samples that under loading was researched and analyzed.?1?Nickel oxide electrode materials that synthesized on the surface of copper foams were prepared by combining one step hydrothermal precipitation method and in situ growth method,the morphology,constitution,structure and electrochemical properties of the prepared samples that under different hydrothermal time were studied.SEM and XRD results indicated that the as-prepared electrode with the hydrothermal time of 6 h has complete microflowers structure,high accumulation density and good crystallization performance.Electrochemical testing indicated that the electrode material with the hydrothermal time of 6 h had the highest specific capacitance,the specific capacitance of it was 1494.8 F�g^-1 at the current density of 0.5 mA/cm²,and the retention rates of specific capacitance after 100 cycles was 70.8%,showing the excellent capacitance and cycle performance.?2?The compression test was applied to the above prepared samples with different hydrothermal time by the means of cyclic loading and unloading.The results of the compression test indicated that the samples with different hydrothermal time were basically in the elastic deformation stage within a loading range of less than 0.3 mm,among them,the elastic modulus of the group of 6 h that under each loading depth was always the smallest.?3?The electrochemical properties of the nickel oxide microflowers electrode that synthesized on the surface of copper foams that after different loading were studied,the results indicated that the internal resistance of the prepared sample increased significantly after compression,and the degree of reversibility of the redox reaction would decrease.The specific capacitance values of the electrode were respectively 1368.4 F�g^-1 and 1348.7 F�g^-1corresponding to the pressed depth of 0.4 mm and 1.2 mm,and the retention rates of specific capacitance after 100 cycles were 70.7%and 65.6%,respectively,showing that the larger the pressed depth,the faster the attenuation of the specific capacitance of electrode,and the worse the cycling performance would be.?4?Acetylene black was used as the carbon source,and nickel oxide/acetylene black microflowers composite electrode materials that synthesized on the surface of copper foams were prepared by combining one step hydrothermal precipitation method and in situ growth method,the morphology,constitution,structure and electrochemical properties of the prepared samples were researched.The results of XRD and SEM confirmed the formation of microflowers structure of NiO&C.The electrochemical tests showed that the NiO/C composite electrode material had lower internal impedance,the specific capacitance of it was 1880 F�g^-1 at the current density of0.5 mA/cm² and the retention rate of specific capacitance after 100 cycles was75.9%,while the corresponding specific capacitance and retention rate of specific capacitance of Ni O were 1494.8 F�g^-1 and 70.8%,which both lower than the one of Ni O/C.The results showed that acetylene black could improve the electrochemical properties of NiO microflowers.?5?The mechanical behavior and electrochemical performance of NiO/C electrode materials that synthesized on the surface of copper foams that after loading were studied,which indicated that the overall elastic modulus of the sample was the largest at the pressed depth of 0.9 mm.However,the elastic modulus was the smallest as the pressed depth was 0.3 mm.The specific capacitance values that under pressure would both reduce,particularly the one under the pressed depth of 0.9 mm was only 1023.2 F�g^-1,which showed that the electrochemical performance of the electrode materials was greatly damaged by high strength loading.