【摘要】 以尿素、四水合氯化锰和氧化石墨烯为原料,采用水热法并通过热分解制备了一种具有石墨烯包覆结构的石墨烯-二氧化锰复合材料,利用扫描电子显微镜、X射线衍射、比表面积(BET)、拉曼光谱和热失重等技术对其形貌、晶体结构及表面结构进行了表征;在三电极条件下利用循环伏安法、恒流充放电法和交流阻抗法测试了材料的电化学性能,并考察了不同石墨烯含量对材料比电容的影响.结果表明,在不添加模板剂的条件下制备的复合材料中二氧化锰是具有介孔结构的α-MnO2,当复合15%(质量分数)的石墨烯后材料的比表面积从109 m2·g-1提高到168 m2·g-1.复合材料具有更好的电化学性能,在0.2 A·g-1电流密度下复合材料的比电容达到最大值(454 F·g-1),远高于纯二氧化锰的值(294 F·g-1).在2 A·g-1的电流密度下恒流充放电2000次后复合材料的比电容保持率为92%.更多还原

【Abstract】 A manganese dioxide(MnO2)-graphene composite material with a unique structure consisting of MnO2 surrounded by graphene sheets was prepared by a simple hydrothermal and thermal decomposition method. The morphology and structure of the obtained materials were examined by scanning electron microscopy, transition electron microscopy, Raman spectroscopy, X-ray diffraction, and N2 adsorption-desorption.Electrochemical properties were evaluated by cyclic voltammetry, galvanostatic charge- discharge and electrochemical impedance spectroscopy. The specific surface area increased from 109 to 168 m2·g-1 for the composite containing 15%(w) graphene. The specific capacitance also increased from 294 to 454 F·g-1 at a current density of 0.2 A·g-1 in an aqueous electrolyte supercapacitor. Moreover, after 2000 cycles of a galvanostatic charge-discharge test, the hybrid electrode still had excellent cycle stability(92% retention rate).更多还原