Towards high power polypyrrole/carbon capacitors
Towards high power polypyrrole/carbon capacitors
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DOI：
10.1016/j.synthmet.2005.07.094
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发表时间：
2005-09-20
期刊：
影响因子：
4.4
通讯作者：
Madden, JD
中科院分区：
文献类型：
--
作者：
Izadi-Najafabadi, A;Tan, DTH;Madden, JD
导电聚合物的有效电容超过100法拉/克，比传统电容器高5个数量级。然而，与传统电容器的毫秒或微秒相反，聚合物放电时间往往在秒的数量级上，使得总功率密度仍然低至少一个数量级。聚吡咯装置本质上是电解电容器，其中充电时间似乎受到离子质量传输速率和RC充电时间的限制。电化学阻抗测量表明，在158 nm厚的聚吡咯膜中的扩散时间常数为33 ms，体积电容为10（7）F/m（3）。测量了高度多孔的聚吡咯/碳复合材料的阻抗，以研究在厚得多的材料中实现类似的快速响应时间。结果表明，增加聚吡咯含量的膜增加电容高达60 F/g，但也增加了充电时间常数。速率限制因素的分析提出了一种优化电容器几何形状以最大化速率的方法，包括预测将导致与传统电容器的功率输送相匹配的器件几何形状。
Conducting polymers demonstrate effective capacitances of more than 100 Farads per gram, 5 orders of magnitude higher than traditional capacitors. However polymer discharge times tend to be on the order of seconds, as opposed to the milli or microseconds of conventional capacitors, so that the overall power density is still at least an order of magnitude lower. The polypyrrole devices are essentially electrolytic capacitors in which charging times appear to be limited by rates of ionic mass transport and RC charging times. Electrochemical impedance measurements suggest diffusion time constants of 33 ms in 158 nm thick polypyrrole films with volumetric capacitances of 10(7) F/m(3). The impedance of a highly porous polypyrrole/carbon composite was measured to investigate the achievement of similarly fast response times in much thicker materials. It is shown that increasing the polypyrrole content of the film increases capacitance up to 60 F/g, but also increases the charging time constant. Analysis of the rate limiting factors suggests a method of optimizing capacitor geometry in order to maximize rates, including the prediction of device geometries that will lead to power delivery matching those of traditional capacitors.