MnO2固态超级电容器的制备及其电化学性能研究

Preparation and electrochemical properties of MnO2 solid supercapacitors

以泡沫镍(NF)为基底,采用恒电位沉积法制备了MnO2电极材料,以聚乙烯醇PVA-Na 2SO 4为凝胶聚合物电解质组装了二电极体系,并以H 2O-Na 2SO 4水系体系为对比进行了电化学性能研究.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X-射线衍射(XRD)对电极材料的形貌和结构进行表征,用循环伏安法(CV)、恒电流充放电(GCD)和交流阻抗(EIS)对电极材料及MnO2//H 2O-Na 2SO 4//MnO2和MnO2//PVA-Na 2SO 4//MnO2体系的电化学性能进行测试.结果表明,MnO2在NF上形成疏松多孔的二维纳米片网络结构;1 A·g^-1电流密度时单电极比电容可达435 F·g^-1;在水系二电极体系中和899.99 W·kg^-1的功率密度下,能量密度可达1.50 W·h·kg^-1,当组建为固态体系时,499.98 W·kg^-1的功率密度下,能量密度可达1.92 W·h·kg^-1,在具有良好的循环稳定性的同时,固态体系相比于水系体系具有更大的工作电压.

A nickel foam(NF)as a substrate,MnO2 is prepared by potentiostatic deposition.Two electrode systems are assembled using PVA-Na 2SO 4 as gel polymer electrolyte,and the electrochemical performance are studied by comparing H 2O-Na 2SO 4.The morphology and structure of depositied MnO2 are characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and X-ray diffraction(XRD).Electrochemical properties are examined by cycle voltammetry(CV),galvanostatic charge-discharge(GCD)and electrochemical impedance spectroscopy(EIS)of MnO2,MnO2//H 2O-Na 2SO 4//MnO2 and MnO2//PVA-Na 2SO 4//MnO2 systems.The results display that MnO2 forms porous two-dimensional nanosheet network structure and specific capacitance is up to 435 F·g^-1 at the current density of 1 A·g^-1 in single electrode system.The energy density can reach 1.50 W·h·kg^-1 at a power density of 899.99 W·kg^-1 in the aqueous electrolyte and 1.92 W·h·kg^-1 at a power density of 499.98 W·kg^-1 in the solid system.Due to excellent cycle stability,the solid system has greater operating voltage than the aqueoussystem.