Construction And Energy Storage Characteristics Of Metal Hydroxide-Based Composite Electrode

Supercapacitor is a new type of green energy storage device,which has the advantages of high power density,long cycle life,wide temperature range,economic and environmental protection,and broad application prospects.Electrode materials are the core factors affecting the performance of supercapacitors.Therefore,the selection and preparation of electrode materials have been widely concerned by researchers.Metal hydroxide electrode materials are suitable for the fabrication of pseudocapacitive supercapacitors because of their high theoretical specific capacitance,good chemical stability,low cost and environmental friendliness.In addition,in order to break through the performance indicators of devices such as high specific capacity and high rate performance,researchers also explored the design and construction of metal hydroxide based composite electrode materials,and optimized the preparation conditions of electrodes by regulating the composite components and preparation paths,so as to obtain the best energy storage characteristics.In this paper,the preparation and energy storage characteristics of metal hydroxide based composite electrode materials are studied.Cu（OH）₂ and Co（OH）₂ based composite electrodes are prepared in situ by electrodeposition technology using copper/nickel foam as electrode substrate.Specific work is as follows:1.Cu（OH）₂ /Ni₃S₂ composite electrode was in-situ constructed on copper foam（CF）substrate by two-step electrodeposition technique.In the first step,Cu（OH）₂ nanorods are generated on the surface of CF by constant current deposition.CF is not only the electrode base,but also the only source of copper.In the second step,Ni₃S₂ layer was uniformly coated on the surface of Cu（OH）₂ nanorods by electrodeposition at constant potential,and the effect of Ni₃S₂ deposition time on the performance of the composite electrode was systematically studied.Thanks to the selection of composite components and electrodeposition preparation technology,especially the introduction of Cu（OH）₂ provides skeleton support and large specific surface area for Ni₃S₂ electrodeposition.The Cu（OH）₂ /Ni₃S₂ composite electrode exhibits enhanced electrochemical performance,with a specific capacity of 11.43F/cm² at a discharge current density of 2 mA/cm².After 5000 cycles,the specific capacity remained at 83.33%of the initial value.2.Co（OH）₂ /Ni₃S₂ composite electrode was in-situ constructed on nickel foam（NF）substrate by two-step electrodeposition technique.The first step is to generate uniform Co（OH）₂ nanosheets on NF surface by constant current deposition.In the second step,Ni₃S₂ layer was deposited at constant potential,and Co（OH）₂ /Ni₃S₂ composite structure was formed at room temperature.The introduction of Co（OH）₂ not only acts as an electrochemically active component,but also provides support for the growth of Ni₃S₂ .In addition,the deposition amount of Ni₃S₂ was regulated by changing the deposition time of Ni₃S₂ ,so as to optimize the energy storage performance of Co（OH）₂ /Ni₃S₂ composite electrode.At the discharge current density of 2 mA/cm²,the specific capacity of the electrode is 5.73 F/cm²,and the coulomb efficiency is as high as 94.14%.The specific capacity retention rate was 84.38%after 5000 cycles of charge and discharge.3.Cu（OH）₂ /NCS composite electrode was obtained by depositing nickel-cobalt bimetallic sulfide（NCS）on the surface of Cu（OH）₂ nanorods by two-step electrodeposition technique.The effect of CH₄N₂ S concentration on NCS deposition was systematically studied.The prepared Cu（OH）₂ /NCS composite electrode has a specific capacity of 7.80F/cm²and a coulomb efficiency of 84.30%at the discharge current density of 2 mA/cm².In addition,at a current density of 40 mA/cm²,the specific capacity remains at 82.93%of the initial value after 5000 cycles.