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

PI: Siegel， donald提案编号：1351482机构：密歇根大学安娜分校标题：职业：锂电池气体演化反应的第一性原理建模这个项目的主要目标是表征与锂空气和锂离子电池阴极内电解质分解相关的反应机制。这些反应发生在电解质/阴极界面，对这些系统的安全性、寿命和效率有重大影响。然而，与发生在相反电极（即电解质/阳极界面）上的现象相比，它们受到的关注相对较少。这种偏差，加上电解质/阴极界面固有的复杂性，导致对阴极介导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，在与现实电池相似的条件下，使用最先进的分子动力学和色散校正密度功能理论模拟，并结合实验方法的设计，将从电极电位、电极表面变化和溶剂化（盐）离子的存在中分离出个体贡献，从而缩小这一知识差距。在大容量锂空气电池中，电解液的分解会形成稳定的化合物（例如碳酸锂），这些化合物需要高过电位才能充电，并且释放二氧化碳而不是O2。在锂离子电池中，电解质-阴极界面的反应会导致CO2、H2等气态物质的积累，当这些气体排放到大气中时，会释放出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将促进合理策略的发展，以尽量减少它们的发生，从而导致更高效和安全的电池。模拟将促进对原型电解质-电极界面的结构、电子、热力学和动力学方面的相互作用的理解。这些界面在诸如燃料电池和光电化学电池等电化学系统中普遍存在。此外，该项目还将把研究成果转化为面向小学、大学和专业学生的能源主题教育活动。在小学阶段，PI将通过为UM科学与工程夏令营的女孩开展为期一周的“能源材料”焦点小组，吸引7 -8年级的女孩。在大学阶段，PI将扩展他现有的课程“材料的原子计算机建模”，开发新的讲座和实验练习，描述将偏置电位引入电子结构计算的方法，以及它们在电化学系统建模中的重要性。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为实习汽车工程师开设的短期课程“电能存储导论”的参与者。这些活动的影响将通过网络和社交媒体进行年度评估，并在选定的情况下进行多年评估。

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.