| As an efficient electrochemical energy storage device,supercapacitor has been widely used in automobile,medical treatment,smart home and other fields.Among many electrode materials for supercapacitors,manganese dioxide in transition metal oxides has attracted much attention,because of its ultra-high theoretical specific capac-itance(1370 F/g),no pollution,and abundant reserves in China.However,manganese dioxide has a series of shortcomings,such as poor conductivity,low energy density,easy agglomeration and so on,so that the actual specific capacitance is not satisfactory,so that the application of manganese dioxide is limited.Therefore,in order to improve the defects existing in manganese dioxide and prepare excellent manganese dioxide electrode materials,two aspects can be realized:one is to choose a material with good conductivity as the base,to compound manganese dioxide with the base,to achieve the advantages of both,so as to improve the electrode performance;Second,different dep-osition methods are used to prepare manganese dioxide with special structure.Some special structures have unique advantages,which can ease the agglomeration phenom-enon of manganese oxide and promote the stability of the overall structure of composite materials.Because nickel foam and carbon cloth both have excellent electrical conduc-tivity and their porous structures can provide more deposition sites,different manga-nese dioxide composites were prepared on nickel foam and carbon cloth substrates by electrodeposition method in this paper to study the influence of substrate and solution composition on electrode material properties.The main work of this paper is as follows:1.Nickel foam is used for the working electrode,platinum net is used for the couterelectrode,and a mixed solution of manganese sulfate and sodium acetate is used for the electrolyte.A working current of 1 m A is set.The relationship between constant current deposition time and electrode material properties was studied.After the prepa-ration of electrode materials,the structure and morphology of the materials were firstly characterized by XRD and SEM,and then a series of electrochemical performance tests such as CV,GCD and EIS were conducted by an electrochemical workstation.Through a series of characterization and testing,it is concluded that the area-specific capacitance of the electrode material is positively correlated with the deposition time of constant current.The electrode material has the best performance when the deposition time is160 min.At the current density of 1 m A/cm~2,the area-specific capacitance of the elec-trode material is 553.8 m F/cm~2.2.Carbon cloth was used for the working electrode,carbon rod was used for the electrode,and a mixture of manganese sulfate and sodium acetate was used for the electrolyte.The cyclic voltammetry(CV)deposition method was used,and the scan-ning rate was set at 20 m V/s.The effect of CV cycles on electrochemical properties of electrode materials was investigated.Firstly,XRD and SEM were used to characterize the structure and morphology of the electrode materials,and then a series of electro-chemical performance tests such as CV,GCD and EIS were conducted using an elec-trochemical workstation.It is concluded that the area-specific capacitance of the elec-trode material is positively correlated with the number of CV deposition.At the same time,the deposition efficiency of manganese dioxide is the highest when the number of CV deposition is 32.At the current density of 1 m A/cm~2,the area-specific capaci-tance reaches 862.8 m F/cm~2.3.The electrolyte was changed into a mixed solution of manganese sulfate,sodium acetate and ammonium sulfate,and carbon cloth was used as the working electrode to study the influence of ammonium sulfate concentration on the electrode material.The results show that the electrode material has the best performance when the ammonium sulfate is 0.175 mol/L,and the area specific capacitance of the material is 1208.89m F/cm~2 when the current density is 1 m A/cm~2. |
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