Abstract

Polypyrroles doped with multiply charged anions are becoming increasingly important in a wide range of energy, environmental and biomedical applications. The increased counterion charge promotes anion binding and retention and can significantly increase stability and performance. The electrochemical properties of polypyrrole films prepared galvanostatically in Na₂SO₄ (PPySO₄) where found to be similar those of PPyClO₄ prepared in NaClO₄, although there was significantly more anion retention during potential cycling. In contrast, PPyPO₄ films prepared in Na₃PO₄ under the same conditions were over-oxidised and more dense, which is beneficial for corrosion protection and electroanalysis. Paradoxically, the low mobility of SO₄²⁻ counterions results in more facile charging and discharging of the film, as observed with large and polymeric counterions. This can create significant benefits in applications that require fast cycling, such as supercapacitors and high-rate batteries. These conclusions are corroborated by electrochemical impedance measurements in various aqueous electrolytes. Ionic conductivity was dominated by anion transport for both PPyClO₄ and PPySO₄, whilst PPyPO₄ was predominantly a cation conductor.

中文翻译：

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抗衡离子电荷对聚吡咯的电化学和阻抗的影响

摘要

在多种能源，环境和生物医学应用中，掺杂有多电荷阴离子的聚吡咯变得越来越重要。抗衡离子电荷的增加促进了阴离子的结合和保留，并可以显着提高稳定性和性能。在Na ₂ SO ₄（PPySO ₄）中通过恒电流法制备的聚吡咯膜的电化学性质与在NaClO _4中制备的PPyClO ₄相似，但在潜在的循环过程中阴离子保留量明显增加。相反，在Na ₃ PO _4中制备的PPyPO ₄膜在相同条件下被过度氧化且密度更高，这对于腐蚀防护和电分析是有益的。矛盾的是，SO ₄ ^2-平衡离子的低迁移率导致薄膜的充放电更加容易，如大型和聚合平衡离子所观察到的。在需要快速循环的应用中，例如超级电容器和高倍率电池，这可以带来巨大的好处。这些结论被各种水性电解质中的电化学阻抗测量所证实。对于PPyClO ₄和PPySO _4来说，离子传导率主要受阴离子迁移的影响，而PPyPO ₄主要是阳离子导体。