CAREER: Dielectric Screening in Structured Polymer Electrolytes

该职业奖支持含离子聚合物材料的理论和计算研究、软件开发和教育工作。这类材料在为手机等轻型电子设备供电的电池中作为分离组件已经显示出巨大的前景。电池中的能量储存和释放依赖于带正电的化学物质在分离介质或电解质中的定向穿梭。传统的电解质通常是一种有效导电离子的液体。通常，这种液体的化学反应过于剧烈，会导致安全问题。聚合物是很有前途的替代品。聚合物是一种大的链状分子，塑料袋、纤维和轮胎都是由聚合物制成的。它们可以在室温下表现为固体，并表现出适度的化学反应性。在这个项目中，PI旨在开发理论和计算工具来了解这些材料的物理和化学性质。PI计划开发理论概念和计算机模拟算法，以解决聚合物电解质设计背后的关键材料科学问题。这个问题的核心是在原子尺度上材料的结构或建筑，材料的形态或形式，以及功能或组件如何相互作用之间的密切联系。为了了解多种可能的特性，将开发理论方法和计算算法，以实现跨长度尺度的候选聚合物电解质材料的模拟。这些努力将得到广泛的实验合作的支持，这将为推进这些聚合物材料的合理设计提供必要的基本理解。这项研究的更广泛的影响包括通过斯坦福大学的“提高对科学和工程的兴趣”项目来训练高中生。学生将参与设计新的模拟算法，并创建一个材料特性数据库，该数据库将供更广泛的科学界使用，以帮助设计材料。PI将致力于通过教育领先的理论研究人员来解决对定量材料设计至关重要的挑战性问题，从而扩大科学界的多样性。这些努力将通过与当地社区大学的互动来整合。开发的实验性筛选软件包将与公众分享。技术概述：该奖项支持含离子嵌段共聚物介电特性的理论和计算研究和教育，含离子嵌段共聚物是锂离子电池电解质膜中特别有前途的候选者。嵌段共聚物自组装成空间异构形态的能力为在同一材料内同时设计机械性能和离子电导率提供了独特的机会。同时，对低平均介电常数结构电解质中静电相互作用的研究提出了根本性的挑战。低介电常数意味着材料内部的强相关性，而结构电解质需要昂贵的计算才能从泊松方程中解出静电势。确定了四个相互关联的研究目标，以解决介电系数相对较低的结构嵌段共聚物中介电筛选的不同方面。第一个目标是发展非均相聚合物电解质的场理论和一个基于离子聚合物自一致场理论的适应对称性的软件包。第二个目标是确定由熵和静电相互作用的竞争效应所控制的不同相行为，并使在临界点附近的分析理论得以发展。第三个目标是通过将实验与建模相结合来推广Debye-Huckel理论，研究强离子相关性如何影响聚合物共混物的混相性。第四个目标是从原子模拟中提取中尺度溶剂化和筛选参数，揭示这些材料的微观介电筛选机制，为连续介质场论提供基础。这四个目标，跨越理论，模拟和实验，期望提供一个连贯的图像离子相互作用在结构聚合物电解质。本研究代表了对结构聚合物电解质中离子间静电相互作用的基本多尺度研究。不断发展的场理论能够有效地筛选参数空间。执行原子模拟可以估计场论中使用的现象学参数，从而允许对假设进行测试。结合这两种方法提供了一个机会来阐明在介电非均质介质中决定非局部和非线性静电相互作用的基本物理。这可以作为设计粗粒度模拟以研究成分波动的动态和影响的垫脚石。所开发的方法将证明对其他静电驱动的自组装现象在分子水平上的研究是有用的。这项研究的更广泛的影响包括通过斯坦福大学的“提高对科学和工程的兴趣”项目来训练高中生。学生将参与设计新的模拟算法，并创建一个材料特性数据库，该数据库将供更广泛的科学界使用，以帮助设计材料。PI将致力于通过教育领先的理论研究人员来解决和解决定量材料设计中至关重要的挑战性问题，从而扩大科学界的多样性。这些努力将通过与当地社区大学的互动来整合。开发的实验性筛选软件包将与公众分享。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。

NONTECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, software development, and education efforts on ion-containing polymeric materials. This family of materials has demonstrated great promise for use as a separation component in batteries that power light-weight electronic devices such as cell phones. Energy storage and release in batteries relies on the directed shuttling of positively charged chemical species inside a separation medium or electrolyte. The conventional electrolyte is normally a liquid which conducts ions efficiently. Often the liquid can be too chemically reactive, leading to safety concerns. Polymers are promising replacements. Polymers are large, chain-like molecules from which, for example, plastic bags, fibers, and tires are made. They can be engineered to behave as solids at room temperature and show modest chemical reactivity. In this project, the PI aims to develop theoretical and computational tools to understand the physical and chemical properties of these kind of materials.The PI plans to develop theoretical concepts and computer simulation algorithms to address the critical material science problems underlying the design of polymer electrolytes. At the heart of this problem is an intimate connection among the structure or the architecture of the material at the atomic scale, the morphology or the form of the material, and functionality or how the components interact with each other. To understand the multitude of possible properties, theoretical approaches and computational algorithms will be developed to enable simulation of candidate polymer electrolyte materials across length scales. These efforts will be backed by extensive experimental collaborations, which will provide the fundamental understanding necessary to advance the rational design of these polymeric materials.The broader impacts of the research include training high school students through the Raising Interest in Science and Engineering program of Stanford University. The students will participate in the design of novel simulation algorithms and in the creation of a database of materials properties that will be accessible to the broader scientific community to aid in the design of materials. The PI will work to broaden the diversity of the scientific community by educating leading theoretical researchers to solve tackle challenging questions crucial to quantitative material design. These efforts will be integrated through interaction with a local community college. The developed software package facilitating the experimental screening will be shared with the public.TECHNICAL SUMMARYThis award supports a theoretical and computational study and education focused on dielectric properties of ion-containing block copolymers, a particularly promising candidate for use in electrolyte membranes in lithium-ion batteries. The ability of block copolymers to self-assemble into spatially heterogeneous morphologies provides a unique opportunity for engineering the mechanical properties and ion-conductivity simultaneously inside the same material. At the same time, it poses fundamental challenges on studying the electrostatic interaction in structured electrolytes with a low average dielectric permittivity. Low permittivity implies strong correlation inside the materials, and structured electrolytes demand expensive calculations to resolve the electrostatic potential from Poisson's equation. Four interrelated research objectives are identified that address different aspects of dielectric screening in structured block copolymers with comparatively low permittivity. The first objective develops field theory for heterogeneous polymer electrolytes and a symmetry-adapted software package, based on ionic polymer self-consistent field theory. The second objective identifies the distinct phase behaviors governed by the competing effects of entropy and electrostatic interaction and enables the development of analytical theory near critical points. The third objective examines how strong ionic correlation impacts the miscibility of polymer blends by combining experiments with modeling to generalize the Debye-Huckel theory. The fourth objective aims to extract mesoscale solvation and screening parameters from atomistic simulations, which will reveal the microscopic dielectric screening mechanism in these materials and provide the foundation for continuum field theory. These four objectives, which span theory, simulation, and experiments, are expected to provide a coherent picture of ionic interactions in structured polymer electrolytes.This research represents a fundamental multi-scale study of the electrostatic interactions between ionic species in structured polymer electrolytes. Developing field theories enables efficient screening of the parameter space. Performing atomistic simulations enables the estimation of phenomenological parameters used in field theory, and thus allows assumptions to be tested. Combining these two approaches presents an opportunity to elucidate the fundamental physics which dictate non-local and nonlinear electrostatic interactions in dielectrically heterogeneous media. This serves as a stepping stone for designing coarse-grained simulations to investigate the dynamics and effects of composition fluctuations. The developed methodology will prove useful for the study of other electrostatics-driven self-assembly phenomena at the molecular level.The broader impacts of the research include training high school students through the Raising Interest in Science and Engineering program of Stanford University. The students will participate in the design of novel simulation algorithms and in the creation of a database of materials properties that will be accessible to the broader scientific community to aid in the design of materials. The PI will work to broaden the diversity of the scientific community by educating leading theoretical researchers to tackle and solve challenging questions crucial to quantitative material design. These efforts will be integrated through interaction with a local community college. The developed software package facilitating the experimental screening will be shared with the public.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.