Soumya M S, Binitha G, Praveen P, Subramanian K R V, Lee Y S, Nair V Shantikumar, Sivakumar N
J Nanosci Nanotechnol. 2015 Jan;15(1):703-8. doi: 10.1166/jnn.2015.9172.
In this work we report the electrochemical performance comparison of two new hybrid supercapacitors one based on graphene as negative electrode and lead dioxide thin film as positive electrode and the other with graphene as negative electrode and lead dioxide-carbon nanotube composite as positive electrode in 0.1 M KOH electrolyte. In the present work, PbO2 was synthesized using sol-gel method which is one of the promising materials for hybrid supercapacitors. The XRD confirmed the single phase of the PbO2 and the grain size is 39 nm which has been determined using Scherrer's formula. Thin films of PbO2, PbO2-CNT composite and graphene were coated on the titanium substrate by electrophoretic deposition. Further material characterisation has been carried out using SEM, TEM, XPS and electrochemical characterisation using CV, charge/discharge and electrochemical impedance spectroscopy (EIS) for obtaining energy density and power density, cyclic stability and internal resistance respectively. The present results revealed that PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibits large specific capacitance and energy density over PbO2/graphene based system. The PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibited maximum power density and energy density of 1200 W/Kg and 65 Wh/Kg respectively at a current density of 2 A/g. The PbO2-CNT composite/graphene asymmetric hybrid system exhibited excellent cycling stability with the capacitance retained 85% of its maximum value up to 3000 cycles.
在本工作中，我们报告了两种新型混合超级电容器的电化学性能比较，一种以石墨烯为负极、二氧化铅薄膜为正极，另一种以石墨烯为负极、二氧化铅-碳纳米管复合材料为正极，电解液为0.1 M KOH。在本工作中，采用溶胶-凝胶法合成了PbO₂，它是混合超级电容器中有前景的材料之一。XRD证实了PbO₂的单相性，利用谢乐公式确定其晶粒尺寸为39 nm。通过电泳沉积将PbO₂、PbO₂-CNT复合材料和石墨烯薄膜涂覆在钛基底上。使用SEM、TEM、XPS进行了进一步的材料表征，并使用CV、充放电和电化学阻抗谱（EIS）进行了电化学表征，分别以获得能量密度和功率密度、循环稳定性和内阻。目前的结果表明，PbO₂-CNT复合材料/石墨烯不对称混合超级电容器比基于PbO₂/石墨烯的体系表现出更大的比电容和能量密度。在2 A/g的电流密度下，PbO₂-CNT复合材料/石墨烯不对称混合超级电容器的最大功率密度和能量密度分别为1200 W/Kg和65 Wh/Kg。PbO₂-CNT复合材料/石墨烯不对称混合体系表现出优异的循环稳定性，在高达3000次循环时电容保持其最大值的85%。
