Development of Molecular Simulation Methods to Compute Interfacial Properties of Electrolytes

纽约州立大学布法罗分校的杰弗里·埃尔林顿获得了化学系理论、模型和计算方法项目的支持，以开展分子模拟方法的开发，以计算电解液的界面性质。该奖项由CBET的界面过程和热力学项目共同资助。PI和他的研究小组开发了基于自由能的方法，通过与严格的热力学关系相联系来研究系统的界面性质。该组织采取了两种方法。第一种方法是通过测定体系的表面过剩自由能与表面密度的关系来计算接触角和固-液界面张力。与通常使用的纳米液滴接触角方法相比，自由能方法具有许多优点。第二种方法是通过面积采样技术测定气液界面张力，通过测量体系自由能随界面面积的变化而推算出界面张力。这项研究涉及将计算自由能的转移矩阵蒙特卡罗方法扩展到电解质的研究。许多技术(如电池、燃料电池)都含有与一个或多个固体表面接触的电解液。在许多情况下，这种器件的性能受电解液-固体界面的性质影响很大。因此，这些应用程序的设计得益于关于系统内微观基质-流体和流体-流体相互作用之间的关系以及它所表现出的宏观性质的基本知识。这种类型的信息提供了对如何调整底物的化学和/或结构以获得所需行为的洞察。本科生和研究生都参与了这项研究。PI已经启动了一个面向中学生的外展项目，重点是锂离子电池及其工作原理。

Jeffrey Errington of the State University of New York at Buffalo is supported by an award from the Theory, Models and Computational Methods program in the Chemistry division to carry out the development of molecular simulation methods to compute interfacial properties of electrolytes. The award is co-funded by the Interfacial Processes and Thermodynamics program in CBET. The PI and his research group develop free energy-based methods to study interfacial properties of a system via connection to rigorous thermodynamic relationships. The group pursues two approaches. The first technique focuses on the evaluation of contact angles and solid-fluid interfacial tensions via determination of the surface density dependence of the so-called surface excess free energy of a system. The free energy approach has a number of advantages over the commonly-used nanodroplet route to the contact angle. The second method focuses on the determination of liquid-vapor surface tensions via area sampling techniques, which deduce the interfacial tension via measurement of the change in system free energy upon variation of the interfacial area. The research involves extending the use of transition matrix Monte Carlo methods to compute free energies to the study of electrolytes. Numerous technologies (e.g. batteries, fuel cells) contain an electrolytic fluid in contact with one or more solid surfaces. In many cases the performance of such devices is influenced significantly by the properties of the electrolyte-solid interface. It follows that the design of these applications benefits from fundamental knowledge regarding the relationship between microscopic substrate-fluid and fluid-fluid interactions within a system and the macroscopic properties it exhibits. Information of this type provides insight into how the chemistry and/or structure of a substrate can be tuned to obtain a desired behavior.Both undergraduates and graduate students are involved in this research. The PI has initiated an outreach program to middle school students that focuses on lithium-ion batteries and how they work.