掺杂离子对聚吡咯膜的电化学容量性能的影响

Effect of Doping Ions on Electrochemical Capacitance Properties of Polypyrrole Films

用电化学方法制备了分别以对甲基苯磺酸根(TOS-),高氯酸根(ClO4-)和氯离子(Cl-)掺杂的聚吡咯(PPy)膜.用循环伏安(CV)、恒电流充放电和电化学阻抗谱(EIS)等测试了它们的电化学容量性能.用扫描电镜(SEM)和X射线衍射(XRD)分别研究了这三种PPy膜的形貌和结构.研究发现,由于具有疏松多孔的形貌和更有序的分子链结构,PPy-TOS和PPy-Cl膜具有较好的充放电能力,在深度充放电时仍具有很小的电化学电阻,其离子扩散接近理想电容器的离子扩散机理.PPy-Cl(聚合电量2mAh·cm-2)的比容量在扫描速率为5mV·s-1时高达270F·g-1,扫描速率200mV·s-1时仍高达175F·g-1,特别是,其比能量高达35.3mWh·g-1.PPy-TOS由于有质量较大的掺杂离子(TOS-)因而比容量略低(146F·g-1,扫描速率5mV·s-1),但具有超快速充放电能力,在扫描速率为200mV·s-1时,比容量为123.6F·g-1,其比功率高达10W·g-1.并且,两种电极材料均具有稳定的电化学循环性能.

Conducting polypyrrole films （PPy） doped with p-toluenesulfonate （TOS^-）, ClO4^-, and Cl^- were electrochemically prepared, respectively. The electrochemical capacitance properties of the PPy films were investigated with cyclic voltammetry （CV）, galvanostatic charge/discharge, and electrochemical impedance spectroscope （EIS） techniques. The morphology observation and structure analysis of PPy films were performed by scanning electron microscope （SEM） and X-ray diffraction （XRD）. The results showed that PPy-Cl and PPy-TOS were characterized with a highly porous and ordered structure, which led to their fast ion switch processes. Moreover, they exhibited a rectangle-like shape of voltammetry characteristics even at a scanning rate of 50 mV·s^-1, a linear variation of the voltage with respect to time in charge/discharge process and almost ideal capacitance behavior in low frequency even on deeply charged/ discharged states in 1 mol·L^-1 KCl solution. Furthermore, specific capacitance of PPy-Cl （polymerization charge of 2 mAh·cm^-2） would reach 270 F·g^-1 （scanning rate of 5 mV·s^-1） or 175 F·g^-1 （scanning rate of 200 mV·s^-1） and its specific energy could reach 35.3 mWh·g^-1. Moreover, with heavier doping ion （TOS^-）, PPy-TOS （polymerization charge of 2 mAh·cm^-2） had a slightly smaller specific capacitance （146 F·g^-1, scanning rate of 5 mV·s^-1） but very rapidly charge/discharge ability （specific capacitance of 123.6 F·g^-1 at scanning rate of 200 mV·s^-1） and its specific power could reach 10 W·g^-1. In addition, both PPy-TOS and PPy-Cl had a good cycleability. All of the above implied that the PPy-Cl and PPy-TOS were two kinds of promising electrode material for supercapacitors.