Dynamical Ion Correlations in Polymer Electrolytes

非技术概述由于电池作为移动储能设备的作用越来越大，我们的社会要求设计出更强大且操作安全的电池。实现这一需求的途径之一是寻找新型电池材料，这种材料具有高导电性，但又能抵抗热和其他可能导致安全问题的压力因素。一个吸引人的新候选材料是带电聚合物材料的薄片--被称为聚合物电解质--具有类似塑料的特性，但允许锂和其他离子通过。不幸的是，目前可用的聚合物电解液仍然缺乏现代电池快速充电和放电所需的导电性。设计更好的电池的一个关键缺失因素是对带电聚合物材料中离子如何运动的预测性理解。该项目将寻求通过使用计算机模拟来发展这种理解，这些计算机模拟精确地解释了用于锂离子电池的一类聚合物的化学细节。根据这些模拟的结果，将确定新的聚合物设计，以加快充电速度并减少安全问题，并将其传达给实验研究人员。这项工作的成果还将有助于提出聚合物材料，以促进从受污染的盐类中净化水，并从废流中提取锂等元素，锂是一种稀缺的国内资源。这个项目的计算机模拟和发现将被整合到课程作业中，并传达给下一代科学家和领导者。此外，该项目将通过使研究经验成为他们教育的一部分来吸引高中和本科生研究人员。技术概述最近，人们对将聚合物电解质用作储能和水净化、分离应用的材料产生了相当大的兴趣。在许多这样的应用中，一个关键的性能指标涉及特定离子相对于存在的其他离子的传输的选择性优化。在这样的背景下，最近探索的许多材料涉及离子的浓缩溶液，其中新的物理产生于一个或多个离子的动力学对不同离子的运动的影响(即相互关联)。在这个项目中，PI提出了一个假设驱动的计划，该计划建立在其他小组报告的新实验结果和研究团队的初步模拟结果的基础上，以阐明两大类问题的微观来源和动态离子相关性的影响：(A)聚合物离子液体中的反离子传输；(B)锂离子在盐掺杂的聚合物离子液体中的传输。PI建议使用原子模拟和粗粒度模拟的组合来验证关于此类材料中动态离子关联的机制起源的假设。该研究小组将利用新获得的知识来确定物理化学参数，这些参数利用离子之间的动态关联来实现更高的电导率和/或转移数。该项目将影响基于聚合物材料的电池电解液的发展。这些进展对于建设可持续能源和经济独立于枯竭的石油和天然气资源具有重要意义。PI的计算机模拟和基础进展将被整合到新的课程材料和本科生和研究生的扩展模块中，以说明干燥和水合聚合物电解质的物理。国际和平研究所还将在APS 3月份的会议上组织一次特别的焦点会议，这次会议将把从事这一不同领域不同方面工作的研究人员聚集在一起。此外，该研究项目将被用作招募和培训本科和高中研究人员的手段，特别关注提高计算材料科学研究人员的多样性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARY Because batteries play an ever-increasing role as mobile energy storage devices, our society demands the design of more powerful and yet operationally safe batteries. One pathway toward this demand is the search for new types of battery materials, highly conductive and yet resistant to heat and other stress factors that can cause safety issues. An attractive emerging candidate are thin sheets of charged polymeric material—known as polymer electrolytes—with plastic-like properties and yet allowing for the passage of lithium and other ions. Unfortunately, currently available polymer electrolytes still lack the conductivity required for the fast charging and discharging needs of present-day batteries. A key missing ingredient for designing better batteries is a predictive understanding of how ions move in charged polymeric materials. This project will seek to develop such an understanding by using computer simulations that precisely account for the chemical details of a class of polymers pursued for lithium-ion batteries. Based on the findings of these simulations, new polymeric designs for faster charging and reduced safety concerns will be identified and communicated to experimental researchers. The outcomes of this work will also be useful for proposing polymer materials that facilitate water purification from contaminating salts and extract elements such as lithium, a scarce domestic resource, from waste streams. The computer simulations and findings of this project will be integrated into course work and communicated to the next generation scientists and leaders. Furthermore, the project will engage high school and undergraduate researchers by making research experiences a part of their education. TECHNICAL SUMMARY Recently, considerable interest has arisen in the use of polymer electrolytes as materials for use in energy storage and water purification, separation applications. In many of these applications, a key performance metric relates to the selective optimization of the transport of a specific ion relative to the other ions present. In such contexts, many of the materials recently explored involve concentrated solution of ions, in which novel physics arises from the influence of (i.e. correlations between) dynamics of one or more of the ions on the motion of a different ion. In this project, the PI proposes a hypothesis driven plan which builds on novel experimental results reported by other groups and the research team’s preliminary simulation results, to shed light on the microscopic origins and the influence of dynamical ion correlations in two broad classes of problems: (a) Counterion transport in polymeric ionic liquids; and (b) Lithium ion transport in salt-doped polymeric ionic liquids. The PI proposes to use a combination of atomistic and coarse-grained simulations to validate the hypotheses regarding the mechanistic origin of dynamical ion correlations in such materials. The research team will use newly gained understanding to identify physicochemical parameters which exploit the dynamical correlations between ions to enable higher conductivities and/or transference numbers.The project will impact the development of battery electrolytes based on polymeric materials. Such advances are of relevance for building sustainable energy sources and economic independence from depleting oil and gas resources. The PI’s computer simulations and fundamental advances will be integrated within new course materials and outreach modules for undergraduate and graduate students to illustrate the physics of dry and hydrated polymer electrolytes. The PI will also organize a special focus session at the APS March meeting which will bring together researchers working on different aspects of this diverse field. Further, the research project will be used as a means to recruit and train undergraduate and high school researchers, with a special focus towards enhancing the diversity among computational materials science researchers.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.