Preparation And Electrochemical Performance Of Cobalt-based Electrode Materials

Supercapacitors have become the most important energy conversion and storage systems in renewable and sustainable technologies in recent years.Because of its high power density,Short charge-discharge time and long service life,supercapacitors have made a breakthrough in energy application.In this paper,zinc nitrate,cobalt nitrate as raw materials,urea to provide alkali source,through the control of different reaction conditions,hydrothermal and subsequent thermal annealing treatment to obtain ZnCo₂O₄ products.The results showed that the optimal reaction conditions were the hydrothermal temperature of120℃,the hydrothermal time of 6 h,the ratio of zinc source to cobalt source is 1:2,and the concentration of 5 M hydrochloric acid etched nickel foam as the collecting fluid.Under these conditions,the electrochemical performance of ZnCo₂O₄ product was the best.The preparation of electrode materials under the current density of 1 A/g,the specific capacitance of 1272 F/g,under the current density of 10 A/g,the specific capacitance of 928 F/g,increased to 10 A from 1 A/g/g,electrode material performance ratio of 73%,under the current density of 10 A/g cycle after 2000 times,the specific capacitance retain 75.3%of the initial capacity,show good cycle stability and times willfulness.Use of adhesive and conductive additives can bring new impedance to electrode materials,affect their electrochemical properties,combined with the production work electrode step tedious and easy to cause the electrode material in the process of tablet internal structure partial damage,considering the above factors,in the previous work to explore the optimum reaction conditions,using the hydrothermal method and subsequent thermal annealing treatment of synthetic methods for synthesis of the cobalt acid zinc/nickel foam composite electrode materials.The electrochemical test of the synthesized zco/nickel foam composite electrode material shows that the specific capacitance of the zco/nickel foam composite electrode material is up to 1888 F/g when the current density is 1 A/g,and 1290 F/g when the current density is 10 A/g.When the ratio of zinc cobalt oxide/nickel foam composite electrode material increased from 1 A g-1 to 10 A/g,the ratio performance of zinc cobalt oxide/nickel foam composite electrode material was 68.3%,which was lower than that of pure ZnCo₂O₄ electrode material.The reason may be that during the test,A part of zinc cobalt oxide was found to fall off from the surface of nickel foam,resulting in the decrease of active substances,which led to the subsequent significant reduction in the capacitance value.At current density of 10 A/g,after 2000 consecutive charge and discharge cycles,the specific capacitance retention rate was 85.7%,which indicated that the zinc cobalt oxide/nickel foam composite electrode had better cyclic stability than the pure zinc cobalt oxide electrode.