水热法制备RGO/MnOx复合材料及其电化学电容性能∗

摘要

通过控制水热反应原料中氧化石墨与氯化锰的比例、甲醇的添加量以及水热反应的温度,制备了不同反应条件下的RGO/MnOx复合材料.利用 X射线衍射(XRD)、X 射线光电子能谱(XPS)和场发射扫描电镜(FE-SEM)表征了样品的晶相结构、氧化石墨的不同含氧基团含量、锰的不同化学价态及其比例和微观形貌.利用电化学工作站测试了样品在三电极测试系统下的循环伏安曲线(cyclic voltammetry,CV)、计时电位曲线(chronopotentiometry)和交流阻抗图谱(electrochemical impedance spectroscopy,EIS).电化学测试表明,用1 mol/L Na2 SO4作为电解液,电位范围为0~1 V,充放电电流密度为1 A/g 的条件下,样品的最佳比电容高达289．8 F/g,在充放电电流密度为20 A/g的条件下,比电容仍然有223．9 F/g,并且在充放电密度为5 A/g的的条件下充放电循环1000次后样品的比电容仍然保持在初始比电容的84．5％.%In the present work RGO/MnOx composites were fabracated by a hydrothermal method at different conditions.The crystal structure,chemical state of the elements,and the microstrucuture of the as-obtained samples were chracterized using power X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS)and field emission scanning electron microscopy (FESEM).Moreover,the electrochemical behaviors were evaluated by cyclic voltammogram (CV),galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS)in a three electrod system.The test results showed that the specific capacitance of the optimal sample was calculated to be 289.8 F/g in 1 mol/L Na2 SO4 electroyte at a current density of 1 A/g with a operating window from 0 to 1 V,and its specific capacitance was 223.9 F/g even at a current rate density of 20 A/g.In addition, the capacitance retention ratio of the sample remained 88% after 1 000 cycles at a high current density of 5 A/g.