Pt/Polypyrrole Quasi-References Revisited: Robustness and Application in Electrochemical Energy Storage Research
Pt/Polypyrrole Quasi-References Revisited: Robustness and Application in Electrochemical Energy Storage Research
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铂/聚吡咯准参考文献重温：电化学储能研究中的鲁棒性及其应用
DOI：
10.1021/acs.analchem.1c03552
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发表时间：
2021
影响因子：
7.4
通讯作者：
Rodríguez-López, Joaquín
中科院分区：
文献类型：
--
作者：
Sarbapalli, Dipobrato;Mishra, Abhiroop;Rodríguez-López, Joaquín
选择用于非水电化学测量的参比电极，特别是在能量存储研究中，由于实验时间长（>1天）、缺乏常用Ag/Ag+参比电极（RE）的替代品、引入结电位以及样品污染的可能性而具有挑战性。通常，使用准参比电极（QRE），例如Ag线和Li金属条。然而，电解质成分的微小变化可能导致大的电位漂移，并且它们的表面可能对溶液具有反应性。在这里，我们提出了一种替代QRE的基础上电沉积在Pt线（PPyQRE）封装在玻璃管与商业玻璃料密封的开放端。虽然文献中已经报道了独立式PPyQRE线，但PPyQRE的简单封装克服了QRE的上述缺点，同时提供了更接近RE性能的可靠参考电位。在溶液中的氧化还原介体的循环伏安法和本体电解测试期间，封装的PPyQRE在多个充电/放电循环中表现出稳定的参考电位，在运行约2.25天后具有最小的漂移（约5 mV）。我们还在多层石墨烯锂离子阳极测试过程中测试了我们的参考品的可靠性，这通常涉及在高还原电位（<−3 V vs Fc/Fc+）下长时间（>1天）循环样品。在相同的测试条件下，Ag/Ag+电极导致石墨烯上可观察到的Ag沉积物和大的电位漂移（约50 mV），而PPyQRE没有表现出可测量的漂移，并且显示出当使用Ag/Ag+时被参比漂移掩盖的伏安特征的变化。在PPyQRE的长期使用（约2个月）中，可通过在实验结束时使用二茂铁对进行校准来解决约30 mV的微小参考漂移。这些结果突出了使用封装的PPyQRE作为简单实用的参比电极用于非水储能研究领域中的电化学测量的优点。
Choosing reference electrodes for nonaqueous electrochemical measurements, especially in energy storage research, is challenging due to lengthy experiments (>1 day), the lack of alternatives to the commonly used Ag/Ag+reference electrode (RE), the introduction of junction potentials, and the possibility of sample contamination. Often, quasi-reference electrodes (QREs) such as Ag wires and Li metal strips are used. However, small changes in electrolyte composition can cause large potential drifts, and their surfaces may be reactive to the solution. Here, we propose an alternative QRE based on polypyrrole electrodeposited on Pt wire (PPyQRE) encased in a glass tube with the open end sealed with commercial frits. While freestanding PPyQRE wires have been reported in the literature, simple encasing of the PPyQRE overcomes the above-mentioned drawbacks of QREs while providing a reliable reference potential that is closer to the performance of an RE. During cyclic voltammetric and bulk electrolysis testing of a redox mediator in solution, the encased PPyQRE exhibited stable reference potentials over multiple charge/discharge cycles with minimal drift (∼5 mV) after ∼2.25 days of operation. We also tested the reliability of our reference during the testing of multilayer graphene Li-ion anodes, which often involve cycling samples at highly reducing potentials (<−3 V vs Fc/Fc+) over long durations (>1 day). In the same testing conditions, the Ag/Ag+electrode led to observable Ag deposits on the graphene and large potential drifts (∼50 mV), while the PPyQRE exhibited no measurable drift and revealed changes in voltammetric features that were obscured by reference drift when using Ag/Ag+. Minor reference drifts of ∼30 mV over long usage of the PPyQRE (∼2 months) can be addressed by calibration with a ferrocene couple at the end of experiments. These results highlight the advantages of using an encased PPyQRE as a simple and practical reference electrode for electrochemical measurements in the field of nonaqueous energy storage research.