The Application Of Cobalt-nickel-based Transition Metal Composite Oxides In Supercapacitor Electrodes

The structure of supercapacitors,As well known,is mainly composed of electrode,electrolyte,diaphragm,collector and shell.The properties of supercapacitors are determined by the electrochemical characteristics of electrode materials.The research on base metal materials with low cost and excellent electrochemical properties has become a hotspot although precious metal materials such as ruthenium?Ru?have the best electrochemical properties.Thus,cobalt-based binary transition metal?hydrogen?oxides?for example Co?OH?₂ and Co₃O₄?as well as cobalt-nickel based ternary transition metal complex oxides?for example CoNiO₂?are regarded as the object in our experiment.Nickel foam is used as the collector.1 M KOH soluble is used as electrolyte.Electrodes containing Co?OH?₂,Co₃O₄ and CoNiO₂ active materials for supercapacitor were prepared by mechanical cold pressing under 8 Mpa.Furthermore,the effects of three active materials on the electrochemical properties of these electrodes were analyzed by the electrochemical workstation.Firstly,the electrochemical properties of electrodes containing Co?OH?₂ and Co3O4 were measured in 1 M KOH electrolyte.The energy storage mechanism and the electrochemical properties of these electrodes were analyzed.The results indicate that?1?The specific capacitance of the electrodes containing Co3O4 is bigger than that of the corresponding electrodes containing Co?OH?₂ at the same scanning rate;?2?The specific capacitance,energy density and power density of the electrodes containing Co3O4 are significantly bigger than those of the electrodes containing Co?OH?₂ at current density of 2.5 mA/cm²;?3?The AC impedance characteristics of the electrodes containing Co3O4 are better than those of the electrodes containing Co?OH?₂ in the frequency range of 0.01-100 kHz and the amplitude of 5.0 mV.Secondly,the electrochemical properties of electrodes containing CoNiO₂ were also measured in 1 M KOH electrolyte.The energy storage mechanism and the electrochemical performance of these electrodes containing CoNiO₂ and Co₃O₄ were analyzed.The results indicate that?1?The specific capacitance of the electrodes containing CoNiO₂ is bigger than that of the corresponding electrodes containing Co₃O₄ at the same scanning rate;?2?The specific capacitance,energy density and power density of the electrodes containing CoNiO₂ are significantly bigger than those of the electrodes containing Co₃O₄ at current density of 2.5 mA/cm²;?3?The AC impedance characteristics of the electrodes containing CoNiO₂ are slightly lower than those of the electrodes containing Co₃O₄ in the frequency range of 0.01-100 kHz and the amplitude of 5.0 mV.Therefore,the specific capacitance,power density and energy density of cobalt-nickel-based ternary transition metal complex oxides are bigger than those of cobalt-based binary transition metal oxides,whereas the AC impedance characteristics of these transition metal complex oxides are slightly lower than those of cobalt-based binary transition metal oxides.