石墨烯负载花球状二氧化锰复合材料制备及其电容性能研究

利用高锰酸钾与乙醇之间的氧化还原反应,在多孔石墨烯表面沉积纳米二氧化锰花球,获得了一种新型的复合电极材料。通过XRD,TG,SEM,TEM等分析手段确定了材料的晶体结构、化学成分、微观形貌特征。电化学性能测试表明:纳米二氧化锰花球具有优异的比电容,但是倍率性能和循环性能不足。通过在石墨烯表面负载纳米二氧化锰花球,能够显著增加石墨烯的比电容,同时改善纳米二氧化锰花球的倍率性能和循环性能。采用0.5mol/L K_2SO_4电解液,进行三电极循环伏安测试,复合电极材料在2mV·s^-1扫速下的比电容高达295F·g^-1,在1000mV·s^-1扫速下,比电容仍然可达102F·g^-1,同时100mV·s^-1,1000次循环后,电容循环保持率可达96.3%。这表明石墨烯负载花球状二氧化锰材料是一种极具潜力的超级电容器电极材料。

Synthesis and capacitive performance of globular MnO_2 flowers anchored graphene composites

A new type globular MnO2 flowers anchored graphene composites was synthesized via redox reactions among potassium permanganate/ethanol/graphene.The crystalline structure,chemical component,and microstructure of the composites were determined by XRD,TG,SEM/TEM and BET analysis.The electrochemical test demonstrates the globular MnO2 material possesses excellent specific capacitance while poor rate capability and cycling stability.By means of anchoring these globular MnO2 flowers onto graphene,the specific capacitance of graphene is significantly improved.Meanwhile,rate capability and cycling stability of the globular MnO2 material can be promoted remarkably.In 0.5mol/L K2SO4 electrolyte,the specific capacitance of the composites reaches as high as 295F·g-1 at 2mV·s-1,and maintains at 102F·g-1 even at a high scan rate of 1000mV·s-1.An outstanding capacitance retention of 96.3% is achieved for the composites after 1000 cycles at 100mV·s-1.It demonstrates the globular MnO2 flowers anchored graphene composites is a very potential electrode material for supercapacitors.