Research On Preparation And Electrochemical Properties Of Co_xS_y/Multilayer Graphene Composites

Supercapacitors have high power density but low energy density,which limits the development of supercapacitors.Cobalt sulfide(Cox Sy)has different valences and has more redox reaction processes,so its supercapacitor performance is better.In this paper,the growth of cobalt sulfide on the surface of multilayer graphene is studied to prepare composite materials with excellent electrochemical properties.(1)A cobalt sulfide/multilayer graphene composite is prepared by subjecting a metal hydroxide/multilayer graphene to a sulfurization reaction.In this paper,a cobalt sulfide/multilayer graphene composite was obtained by preparing a sheet of cobalt-iron double metal hydroxide on the surface of graphene and then performing a sulfurization reaction.The effects of cobalt-iron ratio and vulcanization conditions on cobalt sulfide/multilayer graphene composites were investigated.The experimental results show that the cobalt-iron double metal hydroxide prepared by the ratio of cobalt to iron is 1.6:1,and the composite obtained by the vulcanization reaction for 4 h has the best electrochemical performance.The specific capacity at 1 A/g current density is 324 F/g,the specific capacity retention can reach 47.8% at 10 A/g current density,and 4 A/g current density of 5000 cycles,the specific capacity retention rate is.The composite has good rate performance and cycle performance.(2)Cobalt sulfide/multilayer graphene composites were prepared in situ by solvothermal reaction.The paper studied the effect of cobalt acetate and thiourea addition on the microstructure of cobalt sulfide in composites.The results show that the increase of cobalt acetate and thiourea will increase the content of cobalt sulfide in the composite,but when it exceeds a certain amount,it will cause the accumulation of cobalt sulfide.The paper studied the effect of reaction temperature on the microstructure of cobalt sulfide.The results show that when the reaction temperature is 160 °C,the cobalt sulfide on the surface of the multilayer graphene grows most uniformly.The paper studied the effect of the ratio of cobalt acetate and thiourea on the microstructure of cobalt sulfide.The results show that when the ratio of cobalt acetate to thiourea is 1:0.9,cobalt sulfide exhibits a uniform three-dimensional structure on the surface of multilayer graphene.The results show that the ratio of cobalt acetate to thiourea is 1:0.9,and the cobalt sulfide/multilayer graphene composite prepared by the solvothermal reaction temperature of 160 ° C for 12 h shows the best electrochemical performance.At current densities of 1 A/g and 10 A/g,the specific capacities of the materials reached 422 F/g and 222 F/g.4 A/g current density of 5000 cycles,the specific capacity retention rate is 74.9%,and the cycle stability is better.