The role of electrolyte/cathode interfacial structure on performance of proton exchange membrane fuel cells

电解质/阴极界面结构对质子交换膜燃料电池性能的影响

• 批准号: 0730502
• 负责人: Michael Janik
• 金额: $ 31.89万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0730502&HistoricalAwards=false
• 关键词: role; electrolyte; cathode; interfacial; structure

Proton exchange membrane fuel cells are an alternative energy conversion device that may efficiently convert chemical energy to electrical energy for use as motive power in transportation applications. Inefficiencies in these devices are associated with the energetics of specific chemical processes and constrain their performance. The current state-of-the-art devices can not simultaneously meet efficiency, power output, cost, and durability targets. A majority of the performance losses are allocated to processes at the oxygen reduction cathode, where power/efficiency losses, non-optimum utilization of expensive platinum catalyst, and sensitivity to the reactant oxygen stream relative humidity challenge the development of practical devices. These losses can, in part, be attributed to imperfect design of the Pt catalyst particle-polymer electrolyte interface. However, current attempts to improve the design of this interface are limited by a lack of fundamental understanding of its role in dictating device performance. The complexity inherent in this interface and the need to characterize it under operating conditions limit the ability of experimental techniques to link interfacial structure to PEMFC performance.Intellectual Merit: The research objectives of the proposed work are to (1) appropriately model the membrane/cathode electrocatalytic interface in a proton exchange membrane fuel cell (PEMFC) using both molecular dynamics and quantum-mechanical methods; (2) to describe the influence of humidity and electrochemical potential on the structure of this interface and on oxygen reduction reaction kinetics; and (3) to estimate the losses in PEMFC performance due to a non-ideal electrolyte/electrode interfacial structure. A propose multi-scaled, integrated molecular modeling approach to understand the influence of electrode/electrolyte interfacial structure on oxygen reduction reaction rates is proposed. Molecular dynamics (MD) will be used to probe the structure of this interface as a function of electrode potential and hydration. Quantum-mechanical (QM) methods will be used to quantify the dependence of the elementary oxygen reduction reaction kinetics on this interfacial structure. Method advances in both the application of MD and QM methods to the electrochemical interface will be developed. Collectively, these methods will establish the rate of reaction as a function of hydration and electrode potential, which is directly linked to the PEMFC efficiency and power output. Therefore, the structure of this interface can be linked to PEMFC performance losses thus providing the fundamental structure-performance relationships needed to improve device design. Broader Impact: The proposed work will (1) integrate research efforts in the molecular modeling of energy conversion devices currently concentrating separately on membrane materials and electrode design by probing the interface between these components; (2) enhance ongoing research by training graduate students in the application of molecular modeling techniques to the study of energy conversion processes; and (3) to extend this training beyond the perspective research groups through the development of an advanced course in this area; to involve undergraduates from under-represented groups in research using molecular modeling techniques early in their collegiate careers . An advanced course in molecular modeling emphasizing energy applications will be developed. The modules developed for this course will be made available and publicized to the technical community. Graduate student researchers will receive advanced technical training with additional emphasis on the effective communication of research results. Additionally, components of the proposed study will be offered as research projects through established Penn State programs to recruit and motivate women and minority undergraduate students towards research careers utilizing computational techniques.

质子交换膜燃料电池是一种替代能源转换装置，可以有效地将化学能转化为电能，作为运输应用的动力。这些设备的低效率与特定化学过程的能量学有关，并限制了它们的性能。目前最先进的设备无法同时满足效率、功率输出、成本和耐用性目标。大多数性能损失都分配给氧还原阴极的过程，其中功率/效率损失，昂贵铂催化剂的非最佳利用以及对反应物氧流相对湿度的敏感性对实际设备的开发提出了挑战。这些损失可以部分归因于Pt催化剂颗粒-聚合物电解质界面设计的不完善。然而，由于缺乏对其在决定设备性能中的作用的基本理解，目前改进该接口设计的尝试受到了限制。该界面固有的复杂性以及在操作条件下对其进行表征的需要限制了将界面结构与PEMFC性能联系起来的实验技术的能力。智力优势：所提出的工作的研究目标是：(1)利用分子动力学和量子力学方法适当地模拟质子交换膜燃料电池（PEMFC）中的膜/阴极电催化界面；(2)描述了湿度和电化学电位对该界面结构和氧还原反应动力学的影响；(3)估计非理想电解质/电极界面结构对PEMFC性能的影响。提出了一种多尺度、集成的分子模拟方法来理解电极/电解质界面结构对氧还原反应速率的影响。分子动力学（MD）将用于探测该界面的结构作为电极电位和水合作用的函数。量子力学（QM）方法将被用来量化基本氧还原反应动力学对这种界面结构的依赖。在电化学界面上的应用方面，将发展MD和QM方法的方法进展。总的来说，这些方法将建立反应速率作为水合作用和电极电位的函数，这与PEMFC的效率和功率输出直接相关。因此，该接口的结构可以与PEMFC性能损失联系起来，从而提供改进器件设计所需的基本结构-性能关系。更广泛的影响：拟议的工作将(1)通过探测这些组件之间的界面，整合能量转换设备分子建模的研究工作，目前分别集中在膜材料和电极设计上；(2)加强正在进行的研究，培养研究生将分子建模技术应用于能量转换过程的研究；(3)通过开发该领域的高级课程，将这种培训扩展到视角研究小组之外；让来自代表性不足群体的本科生在其大学生涯早期使用分子建模技术进行研究。将开设一门强调能量应用的分子建模高级课程。为本课程开发的模块将向技术社区提供和宣传。研究生研究人员将接受先进的技术培训，并额外强调研究成果的有效交流。此外，拟议研究的组成部分将通过宾夕法尼亚州立大学已建立的项目作为研究项目提供，以招募和激励女性和少数族裔本科生利用计算技术从事研究工作。