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

本项目将研究约束对高浓度电解质离子结构和动力学的基本作用，并揭示约束如何影响电池系统的性能。当一个物理特征（如孔）的尺寸与存在的分子的尺寸相当时，就会发生约束。多孔电极在电池中很常见，其孔径通常小于50纳米。离子需要在这个受限的孔隙空间内进行导航和电化学反应，才能使电流流动。因此，在电池系统中，电解液动力学和孔隙内的反应性对器件性能至关重要。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遇的推动，特别是在含水电池的新方向，它使用水代替易燃溶剂。尽管他们的承诺，高度浓缩的电解质带来了自己的一系列挑战，加剧了电池系统的限制设置。对高浓度电解质的输运性质的不了解表明，存在独特的结构-性质关系，值得进一步研究，特别是在约束条件下。该项目将在电解质工程方面取得进展，并为改进电极材料/结构以获得更好的电池提供见解。除了电池之外，这一结果还将对胶体凝胶、离子液体和聚合物液体以及一般的受限分子产生重要影响。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。该项目还将提供几个级别的培训。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，当地小学生将通过外展项目学习电池基础知识。该合作项目将通过实验、理论和模型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、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础方面，利用电化学表面力仪（ESFA）、阻抗谱、分子模拟和最近开发的Onsager输运理论等实验技术，为双电层和约束下的输运动力学建立新的理论框架和验证模型。来自这些研究的见解将为m<s:1> nster团队提供输入，他们将从化学和电化学的角度出发，使用不同的电化学和光谱方法，包括拉曼（包括原位表面增强）和红外光谱，以及原位核磁共振和激光光谱，解决edl在多孔电极系统中的非法拉第过程中的作用，以及它对金属电极反应性的影响。本项目将实验技术和理论描述结合起来，研究约束下电解质的力、弛豫和输运行为。该项目是通过“NSF-DFG在密闭空间化学和运输的领导机构活动（NSF-DFG限制）”的机会获得的，这是一项由国家科学基金会和德国科学研究协会（DFG）参与的合作征集。该奖项反映了美国国家科学基金会的法定使命，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.