Evaluation Of Composite Oxide As Supercapacitor Electrode Materials

In addition to concern economic and social development, more countries turned to concern the energy crisis and environmental protection. Energy applications and storage become main issues. As a new type of energy storage devices, Supercapacitors have many advantages. They have attracted much attention because of their advantages. Supercapacitive electrode materials have been a core problem in the fields of electrochemical capacitors. In this thesis, a new type of composite metal oxides has been used as electrode materials. We have analyzed the physical characteristics and electrochemical properties.LSM powders were used as electrode active material to determin electrode fabrication process and test conditions.. Electrodes were manufactured as different mass, shape and sizes by coating method. Analyzing the influence of qulity of electrode active material, uniformity of distribution, shape, sizes and defining the best scanning rage. The results as follow:(1) A supercapacitor has a lower specific capacitance when the qulity of electrode active materials increases. So the qulity of electrode active material is about10mg/cm2in this thesis.(2) The specific capacitance of electrode can not change at different shape and sizes, according to the actual needs, electrode is a1.52cm diameter wafers in this thesis.(3) Cyclic voltammetry was utilized to determine scanning range of LSM electrode which was-0.15-0.42V in6M KOH.As supercapacitor electrode materials, the microstructure and morphology of (La0.75Sr0.25)0.95MnO3±δ powders were examined to analyze electrode electrochemical performance. According to cyclic voltammetry, the specific capacitance of LSM electrode is about16.75F/g at2mV/s.LSM powders were mixed with different amount of Mn(NO3)2and then LSM-MnO2composite powders were obtained by heating. The microstructure and surface areas of composite powders were measured. Meanwhile, a three-electrode system was used to analyze the electrochemical properties of the composite electrodes. The results show that5:1or1:5proportions of composite powders have good electrochemical performance. The whole process of electrode is detailed study, then specific capacitance of electrodes respectively are54.4F/g and106.9F/g at2mV/s scanning rate.Sol-gel method was utilized to synthesize La0.7Sr0.3MnO3powders which presintering temperature respectively was800℃,900℃and1000℃. The influence of different presintering temperature on the physical characteristics of LSM materials was analyzed. And the electrochemical properties of different electrodes were measured in6M KOH. The results indicate that presintering temperature is lower, the specific surface area and specific capacitance of LSM is greater.La0.6Sr0.4Co0.2Fe0.8O3-δ powders were used as supercapacitor electrode materials and the working mechanism of LSCF electrode was detailed investigated. The results show that LSCF electroactive materials have the Faradaic pseudo-capacitance because of redox reaction of Co. Then LSCF and Co(NO3)·26H2O with the ratio of5:1or1:5were mixed. It turned out that the properties of composite powders are better than LSCF materials.