Collaborative Research: Zeolite Thin Films as Efficient and Robust Ion Exchange Membranes in Redox Flow Batteries for Renewable Energy Storage

1263860/1263707东君航/穆拉德，索海尔缺乏经济高效的储能设备是广泛利用可再生太阳能和风能的主要障碍之一。氧化还原液流电池(RFB)因其优良的安全性、高容量、高效率、模块化和环境足迹小而成为一种有吸引力的选择，但在其目前的开发状态下，由于离子交换膜(IEM)的低效，这在很大程度上并不具有商业可行性，而IEM是决定其成本效益、能源效率和电池寿命的关键因素。用于RFBS的IEM的研究和开发工作主要集中在聚合物基材料上。这些材料具有与其聚合物性质相关的基本缺陷，与RFBS的高浓度电解质溶液中的离子交叉和化学不稳定性有关；因此，需要用新材料制造替代的IEM。本项目的目标是探索纳米多孔沸石薄膜作为一种新型的高效耐用的RFB等离子交换膜。一个关键的目标是了解分子筛膜中质子传导和场驱动离子传输的机制。本研究将主要针对Fe/Cr型和全钒型RFB两种模型的MFI型分子筛膜进行研究。具体目标包括：(I)合成不同厚度、取向和骨架组成的MFI分子筛膜，并研究这些结构和化学性质对RFBS中膜性能的影响；(Ii)实验研究质子和相关金属离子在外加电场和不加电场的情况下的输运性质；(Iii)对电场驱动和化学势梯度驱动的离子输运过程进行分子模拟。分子筛膜传输受场驱动的水合质子扩散控制。在本质上是非离子的亚纳米沸石通道中，与水合离子聚合物中的质子跳跃过程有根本的不同。这项研究将使用纳米多孔无机膜，特别是晶态沸石膜，作为新一代高效和坚固的离子交换膜用于RFBS。该项目将通过包括实验研究和分子动力学模拟在内的协同努力，促进关于分子筛膜中离子传输的基础知识。模拟将指导确定最有希望的膜结构和化学性质的努力。更广泛的影响：如果成功，这项研究可能会指导可再生能源间歇性能源存储设备的设计。开发的膜还将在能源生产和环境保护方面具有潜在的应用前景。对分子筛纳米孔中电场驱动的离子传输机制有一个更全面的基础认识，这将是对膜科学的重大贡献。该项目包括实验和理论研究，将为研究生和本科生提供机会。已制定计划，将研究成果纳入现有课程，并纳入来自不同学术和种族背景的本科生参与。这两个私人投资机构都通过研究项目和在研讨会上发表演讲，向高中生和本科生开展外展活动。

1263860 / 1263707 Dong, Junhang / Murad, SohailThe lack of economical and efficient energy storage devices is one of the major hurdles to the widespread utilization of renewable solar and wind energy. The redox flow battery (RFB) is an attractive option because of its excellent safety, high capacity, high efficiency, modularity, and small environmental footprint; however, in its current development state it is not commercially viable largely because of inefficiencies in the ion exchange membrane (IEM), which is a key factor determining its cost effectiveness, energy efficiency, and battery lifetime. Research and development efforts on IEMs for RFBs have largely focused on polymer-based materials. These materials have fundamental deficiencies, associated with their polymeric nature, related to ion crossover and chemical instability in high concentration electrolyte solutions of RFBs; therefore, alternative IEMs fabricated from new materials are required. The goal of this project is to explore nanoporous zeolite thin films as a new class of highly efficient and durable IEMs for RFBs. A key objective is to understand the mechanisms of proton conduction and field-driven ion transport in the zeolite membranes. The research will primarily focus on the siliceous MFI-type zeolite membranes for two model RFB systems including the Fe/Cr RFB and the all-vanadium RFB. The specific objectives include: (i) synthesizing MFI zeolite membranes with different thickness, orientation, and framework composition and investigating the effects of these structural and chemical properties on the membrane performance in RFBs; (ii) experimentally studying the transport properties for proton and relevant metal ions with and without applied electric fields; and (iii) performing molecular simulations of the electrical-field-driven and chemical-potential-gradient-driven ion transport processes. Zeolite membrane transport is governed by the field-driven diffusion of ?hydrated protons? in essentially non-ionic subnanometer zeolitic channels and is fundamentally different from the proton hopping process in the hydrated ionic polymers. This research will employ nanoporous inorganic membranes, particularly the crystalline zeolite membranes, as a new generation of highly efficient and robust IEMs for RFBs. The project will advance fundamental knowledge on ion transport in the zeolite membranes through synergistic efforts involving experimental studies and molecular dynamics simulations. Simulations will guide efforts to determine the most promising membrane structural and chemical properties. Broader Impacts: If successful, this research may guide the design of storage devices for intermittent energy from renewable sources. The membranes developed will also have potential applications energy production and environmental protection. A more complete fundamental understanding of the electrical field-driven ion transport mechanism in zeolitic nanopores will be a significant contribution to membrane science. The project involves experimental and theoretical studies that will provide opportunities for graduate and undergraduate students. Plans have been made to incorporate the research findings into existing courses and to include undergraduate participation from diverse academic and ethnic backgrounds. Both PIs have outreach activities involving high school students and undergraduate students through research projects and presentations at seminars.