Transport Phenomena in Fuel Cells

燃料电池是一种电化学能量转换装置，有望为车辆、家庭和便携式电子产品提供高效、低排放或零排放的电力。拟议研究的长期目标是通过降低性能和成本障碍来促进聚合物电解质膜(PEM)燃料电池的商业部署。 我们建议测量、模拟和预测反应气体、热、质量、水、电荷和质子电荷的转移过程-统称为传输现象-这些对PEM燃料电池的性能和成本至关重要。这些传输现象和产生电能的电化学能量转换发生在膜电极组件(MEA)中。MEA是一个薄的多层结构，由夹在三个不同的多孔层之间的PEM组成：纳米结构的复合催化层、微孔层和纤维气体扩散层。当前技术的许多局限性与缺乏对传输过程及其与MEA多孔层的结构和形态的关系的基本了解有关。 在这个多管齐下的研究计划的第一个轴上，我们将使用层析成像、数值重建和先进的计算建模相结合的方法来解决燃料电池多孔介质纳米结构中的传输现象，包括动态液态水传输。这将提供有关传输过程的有效性及其与多孔层的纳米结构和它们之间的界面的关系的关键信息。 第二个轴将解决如何最终控制制造过程以实现此类设计/结构的问题。催化剂层是通过沉积和干燥由易于团聚的悬浮颗粒组成的“墨水”来制造的。我们将通过对该过程的模拟和新颖的微观可视化来绘制新的方向，以阐明迄今为止通过反复试验而发展起来的制造过程。 第三个轴将综合基本的见解、观察和模型，以a)探索优化运输和催化剂利用的功能化多孔介质；以及b)开发一种双极膜燃料电池，它将阳极上的酸性PEM与碱性阴离子交换膜相结合，允许自我增湿操作，将损失降至最低，并使用更便宜的非贵金属催化剂。 该项目解决了燃料电池商业化的进度问题；进一步拓展了与电池、水过滤和地质碳封存等广泛应用相关的运输现象方面的知识边界；并为培训对加拿大清洁能源部门至关重要的领域的高素质人员提供了令人兴奋的机会。

Fuel cells are electrochemical energy conversion devices that offer the prospect of efficient, low to zero emission power for vehicles, homes and portable electronics. The long-term objectives of the proposed research are to facilitate the commercial deployment of polymer electrolyte membrane (PEM) fuel cells by lowering performance and cost barriers. We propose to measure, model and predict the transfer process of reactant gases, heat, mass, water, electrical and protonic charge—collectively known as transport phenomena—that are central to the performance and cost of PEM fuel cells. These transport phenomena and the electrochemical energy conversion that generates power take place in the membrane-electrode assembly (MEA). The MEA is a thin multilayered structure consisting of a PEM sandwiched between three distinct porous layers: a nanostructured composite catalyst layer; a micro-porous layer; and a fibrous gas diffusion layer. Many of the limitations of current technology are associated with the lack of fundamental understanding of the transport processes and of their relationship to the structure and morphology of the MEA porous layers. In the first axis of this multi-pronged research program we will use a combination of tomographic imaging, numerical reconstruction and advanced computational modelling to resolve transport phenomena, including dynamic liquid water transport, within the nanostructure of the fuel cell porous media. This will provide critical information on the effectiveness of the transport processes and their relationship to the nanostructure of the porous layers and to the interfaces between them. The second axis will addresses the question of how to eventually control the fabrication process to realize such designs/structures. Catalyst layers are fabricated by depositing and drying an “ink” consisting of suspended particles that tend to agglomerate. We will chart new directions with simulations and novel microscopic visualization of the process to shed light on the fabrication process which to date has evolved by trial and error. The third axis will synthesize fundamental insights, observations and models to a) explore functionalized porous media that optimize transport and catalyst utilization; and b) develop a bipolar membrane fuel cell that combines an acidic PEM on the anode with an alkaline anion exchange membrane and which allows self-humidified operation that minimizes losses, as well as use of less expensive non-precious metal catalysts. This program addresses pacing issue in the commercialization of fuel cells; furthers the boundaries of knowledge in transport phenomena relevant to a wide range of applications, including batteries, water filtration, and geological carbon sequestration; and provides exciting opportunities for training highly qualified personnel in areas of critical importance to the Canadian clean energy sector.