构筑高性能的二氧化锰/石墨烯超级电容器

High-performance Supercapacitor of Manganese Dioxide/Graphene

三维泡沫镍(Ni)基石墨烯(graphene)结构具有理想的自支撑特性,但却受制于有限的容量。以三维Ni基graphene为催化基底,通过一步水热法,在三维Ni基graphene骨架上形成二氧化锰/石墨烯/泡沫镍(MnO_(2)/graphene/Ni)的异质结电极。MnO_(2)的形貌随着水热反应温度的增加而呈现出纳米花状、纳米花与纳米棒的混合结构以及纳米棒状。通过循环伏安、恒电流充放电等研究方法,发现具有纳米花状与纳米棒状混合结构的MnO_(2)/graphene/Ni异质结电极,在电流密度为0.1 A·g^(-1)时达到最大比电容193 F·g^(-1),并且在电流密度为1 A·g^(-1)时,经过1000次恒电流充放电后,依然保持104%的初始容量,是一种潜在的电化学性能稳定的超级电容器电极材料。

Three-dimensional Nickel(Ni)-based graphene foam could be used as an ideal framework of supercapacitor electrode,but with a serious limitation of low specific capacity as an electrode material for supercapacitors.Herein,the three-dimensional MnO_(2)/graphene/Ni hybrid foam was successfully prepared on the surface of three-dimensional Ni-based graphene framework by one-step hydrothermal method.The morphology and structure of MnO_(2) grown on graphene could be facilely formed the nanoflowers,the mixed structure with nanoflowers and nanorods,and nanorods with the increasing hydrothermal reaction temperature.The electrochemical properties were evaluated by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD).Based on the mixed structure of MnO_(2) with nanoflowers and nanorods grown on graphene/Ni foam,a maximum specific capacitance of 193 F·g^(-1) was achieved at a current density 0.1 A·g^(-1).In addition,after 1000 charge-discharge cycles at 1 A·g^(-1),the capacitance was retained 104%of its initial capacitance,showing a stable supercapacitor electrode.