掺杂离子对聚吡咯膜的电化学容量性能的影响

用电化学方法制备了分别以对甲基苯磺酸根(TOS-), 高氯酸根(ClO-4)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2 mAh·cm-2)的比容量在扫描速率为5 mV·s-1时高达270 F·g-1, 扫描速率200 mV·s-1时仍高达175 F·g-1, 特别是, 其比能量高达35.3 mWh·g-1. PPy-TOS由于有质量较大的掺杂离子(TOS-)因而比容量略低(146 F·g-1, 扫描速率5 mV·s-1), 但具有超快速充放电能力, 在扫描速率为200 mV·s-1时, 比容量为123.6 F·g-1, 其比功率高达10 W·g-1. 并且, 两种电极材料均具有稳定的电化学循环性能.

Effect of Doping Ions on Electrochemical Capacitance Properties of Polypyrrole Films

Conducting polypyrrole films (PPy) doped with p-toluenesulfonate (TOS-), ClO-4, and Cl- were electro- chemically 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.