Development of Molecular Simulation Methods to Compute Interfacial Properties of Electrolytes

纽约州立大学布法罗分校的Jeffrey Errington获得了化学学部理论、模型和计算方法项目的一项奖励，用于开发计算电解质界面特性的分子模拟方法。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，通过连接严格的热力学关系来研究系统的界面特性。该组织采取了两种方法。第一种技术侧重于通过测定所谓的系统表面多余自由能的表面密度依赖性来评估接触角和固-液界面张力。与常用的纳米液滴接触角方法相比，自由能方法具有许多优点。第二种方法侧重于通过面积采样技术确定液-汽表面张力，该技术通过测量系统自由能随界面面积变化的变化来推断界面张力。该研究涉及将过渡矩阵蒙特卡罗方法用于计算电解质的自由能的应用扩展到研究中。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，这种器件的性能受到电解质-固体界面特性的显著影响。因此，这些应用程序的设计得益于有关系统中微观基质-流体和流体-流体相互作用与宏观特性之间关系的基本知识。这种类型的信息提供了如何调整衬底的化学和/或结构以获得所需行为的见解。本研究涉及本科生和研究生。PI发起了一个面向中学生的推广项目，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.