摘要
以高锰酸钾和醋酸锰为前驱体,通过液相沉淀法合成得到二氧化锰.在不同温度热处理条件下研究二氧化锰的结构转变及其作为超级电容器电极材料的电化学行为.采用X射线衍射(XRD),扫描电镜(SEM),氮气物理吸附和热重(TG)等手段表征产物的结构特点;采用循环伏安和恒流充放电等方法表征其电化学行为.结果表明:合成的二氧化锰是具有中孔特征的α-MnO2,比表面积为253m2·g-1,颗粒尺寸在50-100nm之间.350°C以下的低温热处理使氧化锰仍能保持α-MnO2的晶体结构,比表面积为170m2·g-1左右,单电极比电容值由原来未热解时的267F·g-1增加到250°C热处理后的286F·g-1.高温热处理(>450°C)导致氧化锰逐渐过渡为α-Mn2O3,且表面积下降约为30m2·g-1,比电容急剧下降.低温热处理后氧化锰的电化学稳定性明显提高,在50mV·s-1的快速扫描速率下,电极具有良好的倍率特性.
Manganese dioxide （MnO2） was synthesized using a fluid phase method with potassium permanganate and manganous acetate as precursors. The obtained MnO2 was treated thermally at different temperatures. The structural transformation of MnO2, its electrochemical behavior as an electrode material for use in a supercapacitor were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, N2 physical adsorption, thermogravimetry （TG）, cyclic voltammetry, and galvanostastic charge-discharge. The results indicate that the synthesized MnO2 can be assigned to its α phase and that it possesses a mesoporous feature with a high surface area of up to 253 m2·g-1. After a low temperature thermal treatment （350 °C）, the manganese oxide retained its α-MnO2 crystal structure and its specific surface area was found to be approximately 170 m2·g-1. The specific capacitance of the single electrode increased from 267 F·g-1 for untreated MnO2 to 286 F·g-1 for the sample treated at 250 °C. However, high temperature thermal treatment （450 °C） results in a transformation of the manganese oxide structure to α-Mn2O3 and then to α-Mn3O4. Additionally, the surface area reduced to ca 30 m2·g-1 and this lead to a dramatic decrease in the specific capacitance of manganese oxide. The electrochemical cycling stability of manganese oxide improved noticeably after low temperature thermal treatment and the electrode retained a good rate performance at a scan rate of 50 mV·s-1.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2011年第4期893-899,共7页
Acta Physico-Chimica Sinica
基金
教育部新世纪优秀人才计划(NCET-08-0075)资助项目~~
关键词
二氧化锰
超级电容器
电极材料
热处理
Manganese dioxide
Supercapacitor
Electrode material
Thermal treatment
