Hybrid all-Fe redox flow batteries: Coupling theory and experiment

需要可靠的电能存储设备，以便将更多的高度波动的可再生能源应用到我们的供电电网中。为了使这种能源转换过程也可持续，重要的是使用依赖于地球丰富和无毒材料的储能设备。铁（Fe）满足这些标准，可用于全铁氧化还原液流电池（IRFB），从而为锂离子电池和钒氧化还原液流电池提供了一种有前途的可持续替代品。然而，需要克服跨长度尺度的许多关键挑战才能实现这项技术。在纳米尺度上，需要智能界面设计来抑制寄生的析氢反应。在微观尺度上，多孔3D结构电极必须有利于孔内的可逆Fe电镀和剥离。在宏观尺度上，合适的再平衡系统必须处理析氢，同时需要仔细选择操作条件以减轻由于不期望的Fe电镀/剥离而导致的容量损失。不幸的是，这些障碍不能相互独立地加以解决，而必须同时加以考虑。该项目的目标是建立一个全面的机制的理解IRFB通过使用跨尺度的联合理论和实验方法。只有通过多尺度方法将实验和理论结合起来，才有可能评估，理解和合理地改进这个复杂的系统。从理论方面，我们将结合联合收割机连续和分子模型。随着从电镀和剥离过程中的分子尺度上的操作条件在系统规模的长度尺度，我们将通过应用和推进多尺度建模技术覆盖相关过程。在实验方面，我们将通过将缺陷部位引入平面模型表面来修改表面特性，将所获得的知识整合到3D多孔电极样品中，并在系统级的实际操作条件下测试其特性。理论和实验将通过建立参数化和验证周期来耦合，以获得接口，电极和系统设计的可靠和简洁的建议。

Reliable electrical energy storage devices are required in order to implement more of the highly fluctuating renewable energy sources into our electrical supply grid. To make this energy transition process also sustainable, it is important to use energy storage devices that rely on earth-abundant and non-toxic materials. Iron (Fe) fulfils these criteria and can be used in all-Fe redox flow batteries (IRFB), thereby providing a promising sustainable alternative to lithium-ion batteries and vanadium redox flow batteries. However, many critical challenges across length scales need to be overcome to enable this technology. At the nanoscale, smart interface designs are needed to inhibit the parasitic hydrogen evolution reaction. At the microscale, porous 3D-structured electrodes must facilitate reversible Fe plating and stripping inside the pores. At the macroscale, suitable rebalancing systems must handle hydrogen evolution, while carefully chosen operating conditions are required to mitigate capacity loss due to undesired plating/stripping of Fe. Unfortunately, those obstacles cannot be tackled independent of each other, but must be considered simultaneously. The goal of this project is to establish a comprehensive mechanistic understanding of the IRFB by using a joint theoretical and experimental approach across scales. Only by coupling experiment and theory in a multiscale approach, it will be possible to assess, understand, and rationally improve this complex system. From the theoretical side we will combine continuum and molecular models. With length scales from plating and stripping processes on the molecular scale up to operating conditions at system scale, we will cover the relevant processes by applying and advancing multiscale modelling techniques. On the experimental side we will modify surface properties by introducing defect sites into planar model surfaces, integrate the knowledge gained into 3D porous electrode samples, and test their properties under realistic operating conditions on the system level. Theory and experiment will be coupled by establishing parameterization and validation cycles to arrive at reliable and concise recommendations for interface, electrode and system design.