Brønsted-acidic Ionic Liquids as conducting electrolytes in polymer membrane fuel cells for operating temperatures around 120 °C - Synthesis and electrochemical characterisation.

使用由磺化含氟聚合物（PFSA）制成的膜的聚合物电解质燃料电池（PEFC）在近几十年来为移动的应用设定了标准，并且现在已经达到性能和耐久性的成熟水平。PEFC中的PFSA膜需要足够的水溶胀和进料气体氢气和空气的增湿。这将大气操作限制在<80°C的温度下，因为膜的脱水将显着降低其电导率。在120°C下运行的PEFC可以在高电气性能和更好的热管理下实现更有效的冷却。然而，这些增加的操作温度需要新的电解质材料，其质子传导机制不是基于两性水的存在。非水质子传导电解质也将使主动水管理过时。所有这些都将允许以更简单的设计构建完整的燃料电池系统，从而实现PEFC的更有效的系统集成，特别是在电动汽车领域。中温PEFC将比传统PEFC更好地满足运输和交通部门（汽车、卡车、火车）的要求。为了实现100-140°C之间的操作温度，需要在低水分压下也具有足够质子传导性的新膜材料（非水性）质子传导电解质。在这个项目中，质子传导离子液体（PILs）与强布朗斯台德酸性磺基膦阳离子将被制备和表征。基于磺酸的强酸性和因此强吸湿的PIL是一种有前途的技术方法。重点是不同的极性和亲水/疏水性能和质子传输（车辆或合作机制）和在这样的非水电解质的电极氧化还原反应的动力学的影响的新结构的合成。通过考虑测量的物理和电化学性质，新PIL的结构将在连续的步骤中被优化。在非水电解质中，铂表面上的氧还原反应（ORR）的研究很少。因此，另一个目的也是确定关键的动力学参数，并得到在机制的见解。优化的PIL将被固定在聚合物基质中以获得自立式机械稳定的电解质膜。为了能够开发更高效的未来电池概念，有必要对电催化剂以及新的定制电解质材料进行基础研究。

The polymer electrolyte fuel cell (PEFC) using a membrane made of sulfonated fluoropolymers (PFSA) has set the standards for mobile applications in recent decades and has now reached a mature level of performance and durability. The PFSA membranes in PEFCs require a sufficient water swelling and a humidification of the feed gases hydrogen and air. This restricts the atmospheric operation to temperatures <80°C, as a dehydration of the membrane will decrease its conductivity significantly. A PEFC operated at 120°C allows a more effective cooling at high electrical performance and a better heat management. These increased operating temperatures, however, require a new electrolyte material whose proton conduction mechanism is not based on the presence of the amphoteric water. A non-aqueous proton conducting electrolyte would also make an active water management obsolete. All this would allow to construct complete fuel cell systems with an easier design and thus enable a much more efficient system integration of PEFCs, especially in the field of electro mobility. A medium temperature PEFC would meet the requirements in the transport and traffic sector (cars, trucks, trains) much better than a conventional PEFC. To enable operating temperatures between 100–140°C new membrane materials respectively (non-aqueous) proton-conducting electrolytes with a sufficient proton conductivity also at low water partial pressures are required. In this project, proton-conducting ionic liquids (PILs) with strong Brønsted-acidic sulfoalkylphosphonium cations will be prepared and characterized. Strongly acidic and thus strongly hygroscopic PILs based on sulfonic acids are a promising technological approach. The focus is on the synthesis of new structures with varying polar and hydrophilic/hydrophobic properties and the effect on proton transport (vehicle or cooperative mechanism) and on the kinetics of the electrode redox reactions in such non-aqueous electrolytes. The structure of the new PILs will be optimized in successive steps by considering the measured physical and electrochemical properties. There are only few investigations of the oxygen reduction reaction (ORR) in non-aqueous electrolytes on a platinum surface. Thus, another aim is also to determine the critical kinetic parameters and to get insights in the mechanism. The optimized PIL will be immobilized in a polymer matrix to obtain free standing mechanically stable electrolyte membranes. In order to enable the development of more efficient future cell concepts, it is necessary to proceed with basic investigations on electrocatalysts but also on new customised electrolyte materials.