CDS&E: Organization and Dynamics of Charged Molecules in Heterogeneous Media

CDS

• 批准号: 1611076
• 负责人: Monica Olvera
• 金额: $ 31.5万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1611076&HistoricalAwards=false
• 关键词: CDS& Organization; Dynamics; Charged; Molecules

NONTECHNICAL SUMMARYThis award supports computational and theoretical research, and education on polymer electrolytes. Polymer electrolytes are long chain-like molecules that contain charged units. They are emerging materials for the production and the storage of clean energy in devices such as fuel cell electric vehicles that emit water as exhaust and vehicles powered by rechargeable lithium-ion batteries. Polymer electrolytes are ideal candidates because they are flexible, lightweight, recyclable, and inexpensive. However, polymer fuel cells and batteries have low efficiencies. In order to optimize their efficiency, it is crucial to understand their structure, and how electric charges, or ions, move across the polymer electrolyte material that lies between the terminals and inside these devices. In this project the PI aims to advance fundamental understanding of the complex interplay among different polymer electrolyte phases and the distribution of ions and their motion inside polymer electrolyte materials to enable the design of a nanoscale 'highway system' for ions to travel inside higher performance batteries and fuel cells. The formation of molecular-scale structures called nanostructures within the material guides how ions move. Predictive theoretical and computational tools that can describe and explain the complex behavior of polyelectrolytes could help optimize transport of ions through materials to increase efficiency of energy storage devices. The PI will build on a recently developed approach to describe the effect of inhomogeneities in the polymer electrolyte materials have on the ion motion and on the correlations in the motions of the ions as they move through the materials. The PI aims to develop a self-consistent description that takes into account how the complex distribution of ions and their motions affect the polymer electrolyte material and how the structure of the polymer electrolyte affects the distribution of ions and their motions. Of particular interest is the use of molecular dynamics and other computational methods to analyze ionic transport of charged units confined by interfaces with different materials and their associated electric charges, an important step toward a capability to design nanoscale 'highway systems' for ions to travel inside high performance batteries and fuel cells.Computational tools developed through this project to address problems that arise in materials design have more general application, for example in biological systems and in industrial processes. These tools will enable advances in understanding how molecular units that carry electric charge are confined in small regions as a consequence of an environment made of different materials with different electronic properties. This will help stimulate innovative solutions for manipulating and designing materials for energy storage, as well as nanofluidic devices. Among the impacts derived from this project will be a set of studies compiled into publications and open access programs to assist researchers working in related theoretical and computational soft matter problems. TECHNICAL SUMMARYThis award supports computational and theoretical research, and education on polyelectrolyte blends and copolymers which have been identified as suitable candidate materials for use in high-density energy storage and generation devices. They combine the low volatility and high flexibility of polymers with ion-selective conductivity of the charge-carrying backbone. In polyelectrolyte blends and in neutral-charged copolymer melts, ionic correlations can significantly reduce miscibility, inducing phase separation into nanophases with different concentrations and ordering of ions given that the dielectric constant is relatively low in these materials. Using a hybrid of self-consistent field and liquid state theories, the PI will investigate the nanophase structures formed by copolymer electrolytes, their interfacial properties and ion conductivity. The effect of ionic correlations in polyelectrolyte copolymer melts determines the structure at multiple length scales. The ion distribution depends on the dielectric properties of the media and on the dielectric heterogeneities that developed due to ionic correlations and to the degree of miscibility of the components. The PI will develop models to account for these effects self-consistently. Nanophase segregated structures as well as nanochannels where one dimension is comparable to the Debye length, possess an electrostatic potential that can be significantly modulated by the soft ionic structure inside the channel and by the dielectric heterogeneity at the interface. The ionic concentrations and structure of the nanochannels affect the mechanical and transport properties dramatically. Present studies mainly deal with simple symmetric monovalent electrolytes in aqueous solutions because it is a simple physical system that can be understood by Poisson Boltzmann theory. However, real applications may involve multivalent ion species as well as dielectric interfaces of materials with low dielectric constants. It is therefore crucial to understand the effect of correlations in the structure of charged-neutral copolymer melts, to determine how ions transport through nanochannels. Important effects to determine include the nanostructure symmetry and periodicity which is strongly dependent on ion sizes, molecular weight, copolymer composition and charge distribution along the chains. The PI will implement MD simulations that include ion correlations, finite size of molecules and dielectric heterogeneities to determine the structure of polyelectrolyte copolymer melts and ion conductivities. These simulations, which are based on a true energy functional, are versatile enough to treat the case of multiple and curved interfaces, multivalent salts, and asymmetric ion sizes to study the dynamical evolution of the soft ionic structure. Computational tools developed through this project to address problems that arise in materials design have more general application, for example in biological systems and in industrial processes. These tools will enable advances in understanding of charged soft matter and polymeric materials and will help stimulate innovative solutions for manipulating and designing materials for energy storage, soft electronics, nanofluidic devices, and other application areas. Among the impacts derived from this project will be a set of studies compiled into publications and open access programs to assist researchers working in related theoretical and computational soft matter problems.

非技术摘要该奖项支持聚合物电解质的计算和理论研究以及教育。聚合物电解质是含有带电单元的长链状分子。它们是用于生产和存储清洁能源的新兴材料，例如排放水的燃料电池电动汽车和由可充电锂离子电池供电的车辆。聚合物电解质是理想的选择，因为它们灵活、轻质、可回收且价格低廉。然而，聚合物燃料电池和电池组的效率较低。为了优化其效率，了解其结构以及电荷或离子如何穿过位于端子之间和这些设备内部的聚合物电解质材料至关重要。在该项目中，PI 旨在增进对不同聚合物电解质相之间复杂相互作用以及离子分布及其在聚合物电解质材料内运动的基本理解，从而能够设计纳米级“高速公路系统”，使离子在更高性能的电池内移动和燃料电池。 材料内形成的分子级结构（称为纳米结构）引导离子的移动方式。可以描述和解释聚电解质复杂行为的预测理论和计算工具可以帮助优化离子在材料中的传输，从而提高能量存储设备的效率。该 PI 将基于最近开发的方法来描述聚合物电解质材料中的不均匀性对离子运动的影响以及离子在材料中移动时运动的相关性。该PI旨在开发一种自洽的描述，考虑离子及其运动的复杂分布如何影响聚合物电解质材料以及聚合物电解质的结构如何影响离子的分布及其运动。特别令人感兴趣的是使用分子动力学和其他计算方法来分析受不同材料界面及其相关电荷限制的带电单元的离子输运，这是设计纳米级“高速公路系统”以供离子在内部移动的能力的重要一步高性能电池和燃料电池。通过该项目开发的用于解决材料设计中出现的问题的计算工具具有更广泛的应用，例如在生物系统和工业过程中。 这些工具将有助于理解携带电荷的分子单元如何由于具有不同电子特性的不同材料构成的环境而被限制在小区域内。这将有助于激发操纵和设计储能材料以及纳米流体设备的创新解决方案。该项目产生的影响包括将一系列研究汇编成出版物和开放获取计划，以帮助研究人员研究相关的理论和计算软物质问题。技术摘要该奖项支持聚电解质混合物和共聚物的计算和理论研究以及教育，这些混合物和共聚物已被确定为用于高密度能量存储和发电设备的合适候选材料。它们将聚合物的低挥发性和高柔韧性与带电主链的离子选择性导电性结合在一起。在聚电解质共混物和中性电荷共聚物熔体中，离子相关性可以显着降低混溶性，诱导相分离成具有不同浓度和离子排序的纳米相，因为这些材料的介电常数相对较低。利用自洽场和液态理论的混合，PI 将研究共聚物电解质形成的纳米相结构、其界面特性和离子电导率。聚电解质共聚物熔体中离子相关性的影响决定了多个长度尺度的结构。离子分布取决于介质的介电特性以及由于离子相关性和组分的混溶程度而产生的介电异质性。 PI 将开发模型来自洽地解释这些影响。纳米相分离结构以及一维与德拜长度相当的纳米通道具有静电势，该静电势可以通过通道内的软离子结构和界面处的介电异质性来显着调节。纳米通道的离子浓度和结构极大地影响机械和传输性能。目前的研究主要涉及水溶液中的简单对称一价电解质，因为它是一个简单的物理系统，可以用泊松玻尔兹曼理论来理解。然而，实际应用可能涉及多价离子种类以及低介电常数材料的介电界面。因此，了解带电中性共聚物熔体结构中相关性的影响对于确定离子如何通过纳米通道传输至关重要。需要确定的重要影响包括纳米结构的对称性和周期性，这在很大程度上取决于离子大小、分子量、共聚物组成和沿链的电荷分布。 PI 将实施 MD 模拟，包括离子相关性、分子的有限尺寸和介电异质性，以确定聚电解质共聚物熔体的结构和离子电导率。这些基于真实能量泛函的模拟具有足够的通用性，可以处理多个弯曲界面、多价盐和不对称离子尺寸的情况，以研究软离子结构的动态演化。通过该项目开发的用于解决材料设计中出现的问题的计算工具具有更广泛的应用，例如在生物系统和工业过程中。 这些工具将促进对带电软物质和聚合物材料的理解的进步，并将有助于激发用于操纵和设计能量存储、软电子、纳米流体设备和其他应用领域的材料的创新解决方案。该项目产生的影响包括将一系列研究汇编成出版物和开放获取计划，以帮助研究人员研究相关的理论和计算软物质问题。