Advanced Bipolar Membranes for Energy and Electrodialysis Technology

在外加偏压的情况下，双极膜在质子和氢氧化物导体之间的界面上分解水(H2OàH++OH-)。它正被工业上用于电渗析生产酸和碱，对水和二氧化碳电解槽可能有很大的价值。最近，我们中的一些人介绍了一种新的BPM组装和表征平台，该平台基于膜电极组件(MEA)，用于水电解槽和燃料电池，在运行过程中连续对所有BPM组件施加压力。通过这种方法，我们设计了高活性的BPM，其电流密度达到了创纪录的3 A·cm-2--至少是以前结果的20倍。然而，尽管取得了这些进展，但性能还没有达到新应用程序所需的水平。例如，最好的BPM在2 A·cm-2时分解过电位为~500 mV的水，但在水电解中，总的过电位在2 A·cm-2时必须为&lt；300 mV，包括OER和她的过电位。相反，我们需要更好地了解BPM结，不仅是BPM电解槽和燃料电池，还有电渗析。对于后一种情况，自给自足、独立的BPM仍然具有关键意义，因为多边环境协定太大，不能用于由50-100个串联连接的BPM组成的堆栈。然而，目前尚不清楚传统的、独立的BPM与中东和加勒比地区的BPM之间的性能和结构差异。为了加强科学交流，加快BPM研发，我们需要了解这些差异。在APRICOT，亚琛RWTH(RWTH)和Fritz Haber Institute(FHI)的德国BPM专家将利用法国CNRS中心马赛纳米科学研究所(CINaM)和欧洲膜研究所(IEM)在纳米组装和(2D)材料生长方面的世界专家知识，获得对BPM连接的前所未有的控制和了解。这反过来可能导致高性能的小规模实验室设备，从而推动未来更多的BPM研发。更具体地说，FHI将利用MEA压缩，并将CINaM提供的紧密堆积的纳米颗粒组件和3D图案化薄膜以及IEM提供的(离子选择性)2D材料和ALD薄层集成到MEA-BPM中。通过这种方法，将研究结厚度、形貌、催化剂覆盖率和离子选择性的影响。这使得FHI和RWTH能够根据实验结果开发改进的多物理模型。然后，FHI和RWTH的实验和模拟结果被反馈给IEM和CINaM，以进行进一步的材料优化。此外，FHI和RWTH将研究MEA和独立BPM之间的结构差异和相似之处，以加强这两个平台之间的科学交流和思想的交叉滋养。最后，RWTH将研究水的传输，目标是将FHI最近的高电流密度BPM-MEAs转化为独立的BPM，特别是通过探索IEM和CINaM的精选材料。

Bipolar membranes dissociate water (H2O à H++OH-) at the interface between a proton anda hydroxide conductor under applied bias. This is being exploited industrially in electrodialysis to produce acid and base, and could be of great value for water and CO2 electrolyzers. Recently, some of us introduced a new BPM assembly and characterization platform, based on membrane electrode assemblies (MEAs), which are used for water electrolyzers and fuel cells, and which continuously apply pressure over all BPM components during operation. This way, we designed highly active BPMs with record-high current densities of > 3 A·cm-2 – at least 20 times larger than previous results. However, despite this progress, the performance is not yet at levels needed for new applications. For example, the best BPM dissociates water with an overpotential of ~ 500 mV at 2 A·cm-2, but in water electrolysis the total overpotential must be < 300 mV at 2 A·cm-2, including OER and HER overpotentials. Conversely, we need to better understand the BPM junction, not only for BPM electrolyzers and fuel cells, but also electrodialysis. For the latter, self-supported, free-standing BPMs remain of key significance, as MEAs are too bulky to be used in stacks comprising 50-100 in-series connected BPMs. However, currently, the performance and structural differences between traditional, freestanding BPMs and ones in the MEA are not known. To strengthen scientific exchange and accelerate BPM R&D we need to understand these differences. In APRiCOT, the German BPM experts at RWTH Aachen (RWTH) and the Fritz Haber Institute (FHI) will leverage the world-expert knowledge in nanoassembly and (2D) materials growth of the French CNRS Centre Interdiciplinaire de Nanoscience de Marseille (CINaM) and the Institut Europeen des Membranes (IEM) to obtain unprecedented control and understanding of the BPM junction. This in turn might lead to high performing small-scale lab devices that motivate more BPM R&D in the future. More specifically, FHI will leverage the MEA compression and integrate close-packed nanoparticle assemblies and 3D-patterned membranes provided by CINaM and (ion-selective) 2D materials and ALD thin-layers provided by IEM into MEA-BPMs. This way, the impact of junction thickness, morphology, catalyst coverage and ion-selectivity will be studied. This enables FHI and RWTH to develop improved Multiphysics models alongside experimental results. Then, FHI’s and RWTH’s experimental and simulation results are fed back to IEM and CINaM for further materials optimization. Further, FHI and RWTH will study the structural differences and similarities between MEA- and free-standing BPMs to strengthen scientific exchange and cross-fertilization of ideas between these two platforms. Finally, RWTH will study the water transport and aim at translating FHI’s recent high current density BPM-MEAs into free-standing BPMs, in particular by exploring selected materials from IEM and CINaM.