Veh Philipp, Britton Benjamin, Holdcroft Steven, Zengerle Roland, Vierrath Severin, Breitwieser Matthias
Electrochemical Energy Systems, IMTEK - Department of Microsystems Engineering, University of Freiburg Georges-Koehler-Allee 103 79110 Freiburg Germany
Department of Chemistry, Simon Fraser University Burnaby Canada.
RSC Adv. 2020 Feb 28;10(15):8645-8652. doi: 10.1039/c9ra09628k. eCollection 2020 Feb 27.
Thin ionomer membranes are considered key to achieve high performances in anion exchange membrane fuel cells. However, the handling of unsupported anion exchange membranes with thicknesses below 15 μm is challenging. Typical pre-treatments of KOH-soaking, DI-water rinsing and/or wet assembly with sub-15 μm thin films are particularly problematic. In this work, we report configurations of membrane electrode assemblies with solid polymer electrolyte thicknesses equivalent to 3, 5 and 10 μm, made possible by direct coating of the ionomer onto gas diffusion electrodes (direct membrane deposition). The anion-conducting solid polymer electrolyte employed is hexamethyl--terphenyl poly(benzimidazolium) (HMT-PMBI), which is known for its high mechanical stability and low rate of gas crossover. By fabricating membrane-electrode-assemblies with PtRu/C anodes and Pt/C cathodes with a low precious metal loading of <0.3 mg cm, reproducible performances beyond 1 W cm in H/O atmosphere are achieved. The thin membranes enable excellent performance robustness towards changes in relative humidity, as well as low ionic resistances (<40 mOhm cm).
薄离聚物膜被认为是在阴离子交换膜燃料电池中实现高性能的关键。然而，处理厚度低于15μm的无支撑阴离子交换膜具有挑战性。典型的氢氧化钾浸泡、去离子水冲洗和/或与厚度小于15μm的薄膜进行湿组装预处理尤其成问题。在这项工作中，我们报告了通过将离聚物直接涂覆在气体扩散电极上（直接膜沉积）而实现的膜电极组件配置，其固体聚合物电解质厚度分别相当于3μm、5μm和10μm。所采用的阴离子传导固体聚合物电解质是六甲基-三联苯聚（苯并咪唑鎓）（HMT-PMBI），它以其高机械稳定性和低气体渗透率而闻名。通过制造具有PtRu/C阳极和Pt/C阴极且贵金属负载量低至<0.3mg/cm²的膜电极组件，在H₂/O₂气氛中实现了超过1W/cm²的可重复性能。这些薄膜对相对湿度的变化具有出色的性能稳健性，并且具有低离子电阻（<40mΩ·cm）。
