CAREER: First-Principles Modeling of Gas Evolution Reactions in Lithium Batteries

主要研究者：Siegel，DonaldProposal编号：1351482机构：密歇根大学安娜堡标题：职业生涯：第一原理建模的气体演变反应在锂电池本项目的主要目标是表征与电解质分解内的锂空气和锂离子电池的阴极反应机制。这些反应发生在电解质/阴极界面处，并且对这些系统的安全性、寿命和效率具有重大影响。然而，与发生在相对电极上的那些相比，它们受到的关注相对较少，即，在电解质/阳极界面处。这种偏见，加上电解质/阴极界面固有的复杂性，导致对阴极介导的分解机制的理解有限。该项目将通过在原子尺度上模拟电解质/阴极界面来弥补这一知识差距，在与现实电池中发现的条件类似的条件下，使用最先进的从头算分子动力学和色散校正密度泛函理论模拟，与实验设计方法相结合，将电极电位，电极表面变化，在高容量Li-空气电池中，电解质的分解导致形成稳定的化合物（例如，碳酸锂），其需要高过电位来再充电，并且释放CO2而不是O2。在锂离子电池中，电解质-阴极界面处的反应可导致诸如CO2、H2等气体物质的积累，其在排放到大气中时释放高度易燃的溶剂蒸气。通过揭示与这些分解过程相关的基本步骤，PI将有助于制定合理的策略，以尽量减少其发生，从而提高电池的效率和安全性。模拟将推进理解之间的相互作用的结构，电子，热力学和动力学方面的原型电解质电极界面。这些接口在燃料电池和光电化学电池等电化学系统中普遍存在。此外，本项目还将把研究成果转化为以能源为主题的教育活动，面向小学、大学和专业水平的学生。在小学一级，PI将通过为科学和工程夏令营的UM女孩开发一个为期一周的“能源材料”焦点小组来吸引7 - 8年级的女孩。在学院层面，PI将通过开发新的讲座和实验室练习来扩展他现有的课程“材料的原子计算机建模”，这些讲座和实验室练习描述了将偏置电位引入电子结构计算的方法，以及它们在建模电化学系统中的重要性。最后，在专业层面，将创建一个关于“电池安全”的新模块，并分发给PI为汽车工程师提供的短期课程“电能存储入门”的参与者。“这些活动的影响将每年评估一次-在选定的情况下，将在多年期内-使用基于网络的媒体和社交媒体。

PI: Siegel, DonaldProposal Number: 1351482Institution: University of Michigan Ann ArborTitle: CAREER: First-Principles Modeling of Gas Evolution Reactions in Lithium BatteriesThe primary objective of this project is to characterize the reaction mechanisms associated with electrolyte decomposition within the cathode of Li-air and Li-ion batteries. These reactions occur at the electrolyte/cathode interface, and have major implications for the safety, longevity, and efficiency of these systems. Nevertheless, they have received relatively little attention compared those occurring on the opposing electrode, i.e., at the electrolyte/anode interface. This bias, coupled with the inherent complexity of the electrolyte/cathode interface, has resulted in limited understanding of cathode-mediated decomposition mechanisms. This project will close this knowledge gap by simulating the electrolyte/cathode interface at the atomic scale, under conditions similar to those found in a realistic battery, using state of the art ab intio molecular dynamics and dispersion-corrected Density Functional Theory simulations, in concert with a design of experiments approach that will isolate individual contributions from the electrode potential, variations in the electrode surface, and the presence of solvated (salt) ions.In high-capacity Li-air batteries, decomposition of the electrolyte results in the formation of stable compounds (e.g., Li carbonate), which require high overpotentials to recharge and which release CO2 rather than O2. In Li-ion batteries, reactions at the electrolyte-cathode interface can lead to the accumulation of gaseous species such as CO2, H2, etc., which when vented to the atmosphere release highly flammable solvent vapor. By revealing the elementary steps associated with these decomposition processes the PI will facilitate the development of rational strategies to minimize their occurrence, leading to more efficient and safe batteries. The simulations will advance understanding of the interplay between structural, electronic, thermodynamic, and kinetic aspects of protype electrolyte-electrode interfaces. These interfaces are pervasive in electrochemical systems such as fuel cells and photo-electrochemical cells.In addition, this project will translate research outcomes into energy-themed educational activities for students at the grade school, collegiate, and professional levels. At the grade-school level the PI will engage 7th-8th grade girls by developing a week-long focus group on "Materials for Energy" for the UM Girls in Science and Engineering Summer Camp. At the collegiate level, the PI will extend his existing course, "Atomistic Computer Modeling of Materials," by developing new lectures and laboratory exercises that describe methods for introducing bias potentials into electronic structure calculations, and their importance in modeling electrochemical systems. Finally, at the professional level, a new module on "Battery Safety" will be created and distributed to participants in the PI's short course for practicing automotive engineers, "Introduction to Electrical Energy Storage." The impact of these activities will be assessed annually -- and in selected cases over a multi -year term -- using web-based and social media.