Research On Nanoporous Metal Film Based Supercapacitors

Supercapacitors have attracted worldwide research because of their excellent properties such as high safety,high power density,fast charge/discharge rate and long cycle life and so on.According to the energy storage mechanism,they are generally divided into two categories,electrical double layer capacitors?EDLCs?and pseudocapacitors.The electrode materials for EDLCs are mainly of various carbon nanomaterials with high specific surface area,while for pseudocapacitors that are redox-active transition metal oxides.Because of the different energy storage mechanism,the capacitance of pseudocapacitors is usually 10-100 times higher than that of EDLCs in the same volume.Therefore,the pseudo-capacitive electrode materials have attracted much more research attention,which are mainly focus on transition metal oxides,such as NiO,Co2O3.and MnO2,due to their high theoretical capacitance,low cost and environmental friendliness.The paper studies the electrochemical properties of Ni20Co10Mn70//Ni//Ni20Co10Mn70 alloy based electrodes,which was prepared by dealloying-polarization process.The effect of the thickness of the electrodes on the specific capacitance and energy density was investigated.The rate performance of the NiCoMn alloy based electrodes was greatly enhanced by introducing a middle layer of current collector.The capacitance of the electrode can keep as high as 80%when the current density increases from 1 A cm^-3 to 7 A cm^-3.Meanwhile,the flexibility and machinability of the electrodes were also improved by introducing the middle layer,which provides the prerequisite for automatic large-scale production.The specific capacitance and energy density of the 110 ?m thick electrodes can reach 686.8 F cm^-3 and 46.59 mWh cm^-3,inferring that such electrodes are promising for induistry application.To enhance the electrical conductivity and environment friendliness of the electrode materials and lower price by using less amount of expensive metals,the effect of Cu doping on the performance of the NiCoMn electrode was explored.Herein,Ni20Co5Cu10Mn70,Ni20Co10Cu5Mn70 were used as example for mother-alloy.The electrochamical performance of the obtained electrodes prepared by dealloying and polarizing mother-alloy is investigated.The electrode prepared using Ni20Co5Cu10Mn70 alloy has the characteristics of high electric conductivity and wide potential window.The specific capacitance and current density of the electrode are only 194.9 F cm^-3 and 12.76 mWh cm^-3 at the current density of 1 A cm^-3.While,the electrode prepared using np-Ni20Co10Cu5Mn70 possesses the specific capacitance and energy density of only 266.5 F cm^-3 and 16.32 mWh cm^-3,respectively.