Preparation and Characterization of Highly Stable Ionomers and Ionomer Membranes for Medium Temperature Fuel Cells

在这一建议的基本方法是高度稳定的燃料电池膜和膜电极组件的意图。作为第一步，我们将合成磺化芳香单体和模型化合物，并使用不同的吸电子基团进行修饰，从而稳定磺酸，并使用不同的方法来研究它们的稳定性，如热重(TGA)-红外光谱耦合实验（热稳定性，热分解产物的鉴定）；电子自旋共振（ESR）（自由基攻击稳定性）；环伏安法（电化学稳定性）；储存于水、含水酸、含水碱、含水氧化剂中（在这些溶剂中的稳定性，可从储存后离子交换容量的变化中读出）。在第二步中，选择稳定性最高的单体将通过合适的方法进行聚合（亲核位移聚合和其他缩聚，铃木偶联等），并研究其稳定性。作为第三步，将制备新型聚合物的膜。这些膜也可以通过已知的方法进行交联，以限制水的吸收。此外，这些膜将选择性地掺杂无机化合物，以提高它们的储水能力、100°C以上温度下的质子导电性和热稳定性。通过项目合作伙伴实验室可用的方法，还将对膜的热和（电）化学稳定性进行表征。第四步，从表现出最佳热（电）化学稳定性的膜中制备膜电极组件，也使用各自项目合作伙伴制备的催化剂和电极，并将在PEFC和DMFC中进行表征和测试。该项目的一个重要方面是研究电-电解质界面以及该界面上聚合物离聚体的功能和性质。这些研究的目标是使电极的更合理的改进，特别是电极与来自ICVT的聚芳基离聚体组分。为了深入了解聚合物电解质燃料电池（PEFCs）催化活性层的过程，需要开发不同的新策略。

In this proposal a fundamental approach for highly stable fuel cell membranes and membrane-electrode assemblies is intended. As a first step, sulfonated aromatic monomers and model compounds additionally modified with different electron-withdrawing and therefore sulfonic acid-stabilizing groups will be synthesized and investigated in terms of their stability using different methods like thermogravimetry (TGA)-FTIR-coupling experiment (thermal stability, identification of thermal decomposition products); electron spin resonance (ESR) (radical attack stability); cyclovoltammetry (electrochemical stability); storage in water, aqueous acid, aqueous base, aqueous oxidants (stability in these solvents, readable from the change in ion-exchange capacity after storage). In a second step, the selected monomers with the highest stabilities will be polymerised via suitable methods (nucleophilic displacement polymerisation and other polycondensations, Suzuki coupling, etc.), and also investigated in terms of their stability. As a third step, membranes of the novel polymers will be prepared. These membranes can also be additionally cross-linked via known methods to limit water-uptake. Moreover the membranes will optionally be doped with inorganic compounds to improve their water storage ability, proton conductivity at T more than 100°C, and their thermal stability. The membranes will also be characterized in terms of their thermal and (electro)chemical stability via the methods available in the labs of the project partners. As a fourth step, from the membranes showing the best thermal and (electro)chemical stabilities membrane-electrode assemblies will be prepared, also using catalysts and electrodes prepared by the respective project partners, and will be characterized and tested in both PEFC and DMFC. One important aspect of the project is the investigation of the electrodeelectrolyte interface and the function and properties of the polymeric ionomers at this interface. The goal of these investigations is to enable a more rational improvement of the electrode, in particular electrodes with poly-arylene-based ionomer components from the ICVT. Different new strategies to obtain insight into the processes of the catalytically active layer of the polymer electrolyte fuel cells (PEFCs) are to be developed.