Electrochemical pressure impedance spectroscopy for transport characterization in electrochemical cells

电化学压力阻抗谱(EPIS)显示了对气态反应物(Grübl，Bessler等人)细胞中的传输过程的高度敏感性。2016)。这一新技术基于对电流激励/压力检测或压力激励/电压检测的动态电流/电压/压力行为的分析，频率范围在100 Hz到1 MHz之间。对于聚合物电解质膜燃料电池(PEMFC)，EPIS有望高精度地观察流动和传质现象。这些现象包括气体扩散层和催化剂载体中的气体传输以及产出水的排出，这些现象控制着电池在大电流操作下的性能。输运现象的多样性，它们与电化学和温度的耦合，以及对孔尺寸和尺寸分布等结构属性的依赖，使得理解和建模变得困难。对于传统技术，特别是电化学阻抗谱(EIS)，传输现象很难相互区分，而且它们的信号可能被电荷转移过程(部分)掩盖。支持本提议的关键假设是，EPIS可以显著提高PEMFC中与传输相关的现象的测量灵敏度和准确性。因此，我们建议对质子交换膜燃料电池的EPIS进行实验和建模相结合的研究。具有压力激励和检测的单电池装置将由CNRS洛林大学(法国CNRS)开发和运行。奥芬堡应用科学大学(HSO，德国)将开发一个动态多物理模型并用于数据分析。本研究的主要目的是开发和评价用于质子交换膜燃料电池诊断的EPIS。此外，预计这项调查将对了解、表征和量化电池中涉及气体和液态水的不同传输现象做出重大贡献。最后，将测试低成本压力激励和/或检测设备的使用，如扬声器和/或压力传感器，以便显著降低总体诊断技术的成本。我们的愿景是，EPIS能够成为日常实验室实践中的标准诊断工具，以有限的附加工作(财务和技术)补充EIS，但大大增强输出。为期三年的项目将包括两个合作伙伴之间的持续互动，CNRS负责实验部分和数据生成，HSO致力于模型开发和数据解释。一揽子工作包括实验和模型的准备阶段；包括测量装置和模拟工具的EPIS工具的开发和使用；对结果的解释；以及EPIS技术的评价和评估。

Electrochemical pressure impedance spectroscopy (EPIS) shows a high sensitivity towards transport processes in cells with gaseous reactants (Grübl, Bessler et al. 2016). This novel technique is based on analyzing the dynamic current/voltage/pressure behavior by either current excitation/pressure detection or pressure excitation/voltage detection with frequencies in the range of 100 Hz to 1 mHz. For polymer electrolyte membrane fuel cells (PEMFC), EPIS is expected to allow the observation of flow and mass transport phenomena with high accuracy. These phenomena, covering gas transport in the gas diffusion layers and the catalyst support as well as evacuation of the produced water, govern the cell performance at high-current operation. The diversity of transport phenomena, their coupling with electrochemistry and temperature, and dependence on structural properties such as pore sizes and size distributions makes understanding and modeling difficult. With conventional techniques, in particular electrochemical impedance spectroscopy (EIS), transport phenomena are difficult to be distinguished from each other and their signal may be (partially) masked by charge-transfer processes.The key hypothesis governing the present proposal is that EPIS can significantly increase measurement sensitivity and accuracy of transport-related phenomena in PEMFCs. We therefore propose a combined experimental and modeling study of EPIS for PEMFCs. A single-cell setup with pressure excitation and detection will be developed and operated by CNRS - Université de Lorraine (CNRS, France). A dynamic multi-physics model will be developed and used for data analysis by Offenburg University of Applied Sciences (HSO, Germany). The primary goal of the study is the development and evaluation of EPIS for PEMFC diagnosis. In addition, the investigation is expected to bring a significant contribution on understanding, characterization and quantification of the different transport phenomena involving gases and liquid water in the cell. Finally, the use of low-cost pressure excitation and/or detection equipment such as a loudspeaker and/or pressure sensors will be tested, for the sake of significant reduction in the cost of the overall diagnosis technique. Our vision is that EPIS can become a standard diagnosis tool in everyday lab practice complementing EIS with limited add-on effort (financially and technically) but strongly enhanced output.The three-year project will consist in continuous interaction between the two partners, CNRS being in charge of the experimental part and generation of data, HSO working on model development and data interpretation. The work packages include a preparative phase for experiments and models; the development and the use of the EPIS tool covering the measurement device and the simulation tool; interpretation of the results; and evaluation and assessment of the EPIS technique.