CAREER: Investigation of Non-Aqueous Single-Metal Redox Flow Batteries through Experiment and Modeling

智能优点：这项建议侧重于对新型非水、单金属氧化还原液流电池(RFB)的实验和理论研究。这些RFB依赖于金属配位络合物歧化成氧化和还原产物。使用非水液体来支持氧化还原反应，可以将电池电压提高到远高于水分解的范围。我们用第一排过渡金属络合物进行的初步实验表明，一些平衡电压是水体系允许的两倍以上，这表明发展高电导率的溶剂/载体体系和经历多电子转移的高可溶性活性络合物结构可以提高能量密度200%-300%。非水、单金属、基于歧化的RFB有望显著提高性能，而我们的初步循环结果表明，具有竞争力的库仑效率。我们看到非水RFB系统在循环过程中的能量和功率效率相对较低，本研究将解决这些问题。拟议的研究将对非水RFB进行实验观察并使其合理化。我们的目标是在合理的基本原则的基础上指导下一代非水RFB的反应器设计和材料选择。三个相辅相成的项目将在为期五年的研究期间并行执行。(1)用电位法和光谱学方法研究了各种非水RFB体系的平衡电化学性质。我们将在不同的载体和溶剂体系中研究几种三价&二酮金属活性络合物。除了阐明活性和电势如何依赖于RFB系统的荷电状态之外，这项工作还将通过展示溶质/溶质和溶质/溶剂相互作用如何总体上影响RFB的效率来为未来的系统设计提供信息。(2)液体和分离相中的传输现象将通过直流电导、交流阻抗谱和UV-Vis光谱等方法进行表征。结果将与先进的理论多组分传输模型相匹配，并用于支持RFB操作的计算机模拟的属性数据库。将制造RFB电池，以用实验充放电数据来证实数值结果。该模型还将用于预测如何改变控制方案和单元设计，以优化RFB性能。(3)通过电化学实验探索单金属RFB的反应速率和反应机理。将创建理论方法来建立几个活性-络合氧化还原反应的机理。动力学模型将包含在RFB单元模拟中。最终，这项研究计划将提供一个连续尺度的模型，使RFB电池在实际充电和放电过程中在不同充电状态和不同充放电速率下的瞬时电流/电压响应合理化并进行预测。模拟将允许研究各种电极配置、电池设计和电解液流动方案。我们将采取自下而上的方法，使用对整体、界面和阶段交换过程的研究来支持整个RFB的整体、微观信息模型。广泛影响：外展活动将促进我认为存在于研究进展和教学活动之间的自然联系。我的主要外展目标是在多样化的研究环境中倡导多学科、协作的电化学工程教育。这一目标将通过以下方式实现：(1)继续开发包含RFB研究问题的研究生水平的电化学工程课程；(2)通过参与与电化学工程相关的服务活动，提供本科生研究机会，并在课堂外开发思想交流论坛，鼓励本科生对能源系统设计的兴趣；以及(3)参加MI-LSAMP外联计划，旨在增加未被充分代表的少数族裔和妇女对尖端科学、技术、工程和数学的参与。我希望把电化学从化学工程研究的边缘移开。增加各行各业的预科、本科生和研究生对电化学工程的接触，将促进必要的创新，以支持国家向更多样化、更可持续的能源生产转变。

Intellectual Merit: This proposal focuses on experimental and theoretical studies of a new class of non-aqueous, single-metal redox flow battery (RFB). These RFBs rely on disproportionation of metal coordination complexes into oxidized and reduced products. Use of non-aqueous liquids to support redox reactions makes it possible to raise cell voltages well above the range where water decomposes. Our preliminary experiments using first-row transition-metal complexes demonstrate some equilibrium voltages more than twice as large as aqueous systems permit, suggesting that development of high-conductivity solvent/support systems and highly soluble active-complex structures that undergo multiple electron transfer could improve energy density by 200%-300%. Non-aqueous, single-metal, disproportionation-based RFBs promise significantly improved performance over aqueous chemistries, and our preliminary cycling results suggest competitive coulombic efficiencies. We see comparatively low energy and power efficiencies in non-aqueous RFB systems during cycling, issues this research will address. The proposed research will perform and rationalize experimental observations of non-aqueous RFBs. Our goal is to guide reactor design and materials selection for next-generation nonaqueous RFBs on the basis of sound fundamental principles. Three complementary projects will be executed in parallel during the five-year research term. (1) Equilibrium electrochemical properties of various non-aqueous RFB systems will be investigated by potentiometric and spectroscopic methods. Several trivalent β-diketonate metal active complexes will be studied in various support and solvent systems. In addition to elucidating how activity and potential depend on an RFB system?s state of charge, this work will inform future system design by showing how solute/solute and solute/solvent interactions impact efficiency of RFBs in general.(2) Transport phenomena in the liquid and separator phases will be characterized with methods including DC conductimetry, AC impedance spectroscopy, and UV-vis spectroscopy. The results will be matched to advanced theoretical multicomponent transport models, and used to underpin a property database for computer simulations of RFB operation. RFB cells will be fabricated to corroborate numerical results with experimental charge/discharge data. The model will also be used to predict how control schemes and cell design can be varied to optimize RFB performance. (3) Reaction rates and mechanisms in single-metal RFBs will be probed by electrochemical experiments. Theoretical methods will be created to establish mechanisms for several active-complex redox reactions. Kinetic models will be included in RFB cell simulations. Ultimately, this research program will deliver a continuum-scale model that rationalizes and predicts the transient current/voltage response of RFB cells during practical charging and discharging between various states of charge, and at various charge and discharge rates. Simulations will permit studies of various electrode configurations, cell designs, and electrolyte flow schemes. We will take a bottom-up approach, using studies of bulk, interfacial, and phase exchange processes to support a holistic, microscopically informed model of the entire RFB.Broader Impact: Outreach activities will foster the natural connection that I believe to exist between research progress and pedagogical activity. My central outreach objective is to advocate multidisciplinary, collaborative electrochemical engineering education in a diverse research environment. This objective will be addressed by: (1) continuing development of graduate-level electrochemical engineering courses that incorporate RFB research problems; (2) encouraging undergraduate interest in energy-system design by participating in service activities related to electrochemical engineering, offering undergraduate research opportunities, and developing forums outside the classroom for the exchange of ideas; and (3) taking part in the MI-LSAMP outreach program, which aims to increase participation by under-represented minorities and women in cutting-edge science, technology, engineering, and mathematics. I hope to move electrochemistry away from the periphery of chemical engineering research.Increasing the exposure of pre-college, undergraduate, and graduate students from all walks of life to electrochemical engineering will facilitate the innovation necessary to support a national shift to more diverse, sustainable energy production.