NSF-DFG Confine: Structure, dynamics, and electrochemical stability of concentrated electrolytes in confined spaces

该项目将研究限制对高浓度电解质中离子结构和动力学的基本作用，并揭示限制如何影响电池系统的性能。当物理特征（例如孔）的尺寸与存在的分子的尺寸相当时，发生限制。多孔电极在电池中很常见，孔径通常小于50纳米。离子需要在这个有限的孔隙空间内导航和电化学反应，以便电流流动。因此，在电池系统中，孔内的电解质动力学和反应性是装置性能的核心。高浓度电解质是一个新兴的领域，受到更安全和更高能量密度电化学设备的突破性机会的推动，特别是对于使用水代替易燃溶剂的水性电池的新方向。尽管它们的承诺，高浓度电解质带来了自己的一系列挑战，这些挑战在电池系统的有限环境中加剧。对高浓度电解质中的输运性质的认识不足表明，有独特的结构-性质关系在起作用，值得进一步研究，特别是在限制下。该项目将在电解质工程方面取得进展，并为更好的电池提供改进的电极材料/结构。除了电池之外，这些结果还将对胶体凝胶、离子和聚合物液体以及通常受限制的分子产生重要影响。研究水基电解质的见解也可能有助于环境修复应用，如盐水管理。该项目还将提供若干级别的培训。本科生和研究生研究人员将从国际合作中获得独特的视角，当地小学生将通过推广计划了解电池基础知识。这个合作项目将使用实验，理论和模型来揭示受限浓缩电解质的基本结构-性质关系。该团队将从阴离子，阳离子，化合价以及溶剂的介电常数中分离出贡献，以获得对潜在结构和动力学的清晰理解。伯克利团队将专注于基本方面导致新的理论框架和验证模型的双电层和运输动力学约束下使用实验技术，如电化学表面力装置（ESFA），阻抗谱，分子模拟，最近开发的Onsager运输理论。这些研究的见解将为明斯特团队提供输入，他们将从化学和电化学的角度，使用不同的电化学和光谱学方法，包括拉曼（包括原位表面增强）和红外光谱，以及原位NMR和激光光谱，从化学和电化学的角度解决EDLs对多孔电极系统中非法拉第过程的作用及其对金属电极反应性的影响。该项目涉及一种新颖的实验技术和理论描述的约束下的电解质的力，松弛和运输行为的组合。该项目是通过“NSF-DFG领导机构活动在化学和运输在受限空间（NSF-DFG限制）”机会，一项涉及美国国家科学基金会和德国研究共同体（DFG）的合作征集活动该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will investigate the fundamental role of confinement on the ionic structure and dynamics in highly concentrated electrolytes, and reveal how confinement impacts performance of battery systems. Confinement occurs when the dimension of a physical feature, such as a pore, is comparable to the dimensions of the molecules present. Porous electrodes are common in batteries, with pore sizes that are often smaller than 50 nanometers. Ions need to navigate and react electrochemically inside this confined pore space for electrical current to flow. Therefore, in battery systems the electrolyte dynamics and reactivity within pores is central to the device performance. Highly concentrated electrolytes are a burgeoning field driven by groundbreaking opportunities for safer and higher energy density electrochemical devices, in particular for new directions in aqueous batteries, which use water instead of a flammable solvent. Despite their promises, highly concentrated electrolytes bring their own set of challenges that are exacerbated within the confined settings of battery systems. A poor understanding of transport properties in highly concentrated electrolytes suggest that there are unique structure-property relationships at play that warrant further investigation, especially under confinement. This project will yield advancements in electrolyte engineering and offers insights into improved electrode materials/structures for better batteries. Beyond batteries, the results will have important implications for colloidal gels, ionic and polymeric liquids, and generally molecules under confinement. Insights from studying the water-based electrolytes may also aid in environmental remediation applications like brine management. This project will also provide training at several levels. Undergraduate and graduate student researchers will gain unique perspectives from the international collaboration and local elementary students will learn about battery basics through outreach programs. This collaborative project will uncover fundamental structure-property relationships for confined concentrated electrolytes using experiments, theories, and models. The team will isolate contributions from the anion, cation, valency, as well as the dielectric constant of the solvent to obtain a clear understanding of the underlying structure and dynamics. The Berkeley team will focus on the fundamental aspects leading to novel theoretical frameworks and validated models for the electric double layer and transport dynamics under confinement using experimental techniques such as the Electrochemical Surface Force Apparatus (ESFA), impedance spectroscopy, molecular simulations, and recently developed Onsager transport theory. Insights from these studies will provide input to the Münster team who will address the role of EDLs on non-Faradaic processes in porous electrode systems and its influence on the reactivity on metallic electrodes from a chemical and electrochemical standpoint using different electrochemical and spectroscopically methods including Raman (including in situ surface enhanced) and IR spectroscopy, as well as in situ NMR and laser spectroscopy. This project involves a novel combination of experimental techniques and theoretical descriptions for the forces, relaxation and transport behaviors of electrolytes under confinement.This project was awarded through the “NSF-DFG Lead Agency Activity in in Chemistry and Transport in Confined Spaces (NSF-DFG Confine)" opportunity, a collaborative solicitation that involves the National Science Foundation and Deutsche Forschungsgemeinschaft (DFG).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.