Chemical and structural design of inorganic-organic layers for stabilized Li anodes

该项目将产生基础知识，并确定开发基于锂金属的改进电池阳极的设计原则。这一知识对于使可充电高能量密度锂电极电池能够用于基于电动车辆的运输和可再生发电的紧凑存储至关重要。这项工作将促进对这种活性材料如何形成有益的离子导电材料膜的理解，这些膜具有提高稳定性、循环效率和寿命的潜力。这项工作中开发的见解可用于设计新的制造程序和改进具有更高稳定性的锂阳极的界面，这是目前这项技术的关键问题。这项工作可能会导致更轻，更持久，更紧凑的运输电池，这有助于提高国家能源可持续性，减少空气污染，并为更广泛的电动汽车采用提供潜在途径。教育和推广计划将利用并增加马萨诸塞州理工学院的现有项目，以使K-12学生受益，并提高剑桥和大波士顿地区与储能，电池和电化学相关的公众素养。该项目特别需要开发新的教育材料和教学模块，以支持公立学校科学教师教授能源转换和存储概念，并与麻省理工学院埃杰顿中心和麻省理工学院博物馆合作在麻省理工学院校园举办研讨会。PI还计划将大波士顿社区大学的学生纳入夏季研究。可充电锂电极是最有前途的“超越锂离子”先进电池化学的基本元素。然而，锂电极目前无法以可接受的库伦效率、安全性或寿命进行循环。本项目研究氧化物和氟化物气体如何与锂金属相互作用，并赋予有利于形成人工固体电解质界面（SEI）的化学，形态和电化学特性。这项研究包括锂与气体反应的系统研究，这些气体在锂表面产生离子化合物，允许对形成的无机界面进行独立调整和研究。通过探索预计将产生一套全面的不同无机层成分的三种气体，这项工作将有助于对SEI化学，结构和电子特性如何控制性能的新的基本理解，并确定优化的无机层化学，以推动未来的添加剂开发和优化。研究计划的主要任务是：（1）利用X射线光电子能谱、傅里叶变换红外光谱、电子显微镜和热/微观结构模型确定新鲜Li在气体环境中反应时形成的膜的化学和结构性质;（2）进行循环测量并量化库仑效率、循环寿命和短路时间的关键电化学指标;（3）测量反应气体的物理和电化学性质，包括与SEI修复过程相关的反应动力学、传输参数和电池环境中的电化学活性;（4）探索使用这些气体进行修复反应的可行性和机制。这项工作将有助于了解气体分子如何在锂电极表面远离平衡的反应中分解，以及如何利用这种反应性来开发优化的界面，以提高效率和循环寿命。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will generate fundamental knowledge and identify design principles for developing improved battery anodes based on lithium metal. This knowledge is critical for enabling rechargeable high energy density lithium electrode batteries for electric vehicle-based transportation and for compact storage of renewably generated electricity. This work will advance understanding of how this active material forms beneficial, ionically-conductive material films that have the potential to impart improved stability, cycling efficiency and lifetime. The insights developed in this work can be used to design new fabrication procedures and improved interfaces for lithium anodes with higher degrees of stability, which is currently a key issue with this technology. This work could lead to lighter, longer-lasting and more compact transportation batteries, which supports improved national energy sustainability, reduced air pollution, and a potential path to more widespread electric vehicle adoption. The educational and outreach plans will leverage and add to existing programs at the Massachusetts Institute of Technology to benefit K-12 students and improve public literacy related to energy storage, batteries and electrochemistry within the Cambridge and Greater Boston areas. This project specifically entails development of new educational materials and teaching modules to support public school science teachers in teaching energy conversion and storage concepts, and workshops to be hosted on MIT campus in collaboration with the MIT Edgerton Center and MIT Museum. The PI also plans inclusion of Greater Boston community college students in summer research.The rechargeable Li electrode is an essential element of the most promising, "beyond Li-ion" advanced battery chemistries. However, Li electrodes do not currently cycle with acceptable Coulombic efficiency, safety, or lifetime. This project investigates how oxide and fluoride gases interact with Li metal, and impart chemical, morphological, and electrochemical properties favorable to formation of an artificial solid electrolyte interphase (SEI). This research includes systematic studies of Li reactions with gases that yield ionic compounds on the Li surface, allowing for independent tuning and study of the formed inorganic interface. By exploring three gases that are projected to yield a comprehensive set of distinct inorganic-layer compositions, this work will contribute new fundamental understanding of how the SEI chemical, structural and electronic properties govern performance, and identify optimized inorganic-layer chemistries that can drive future additive development and optimization. The major tasks that comprise the research plan are: (1) Determine the chemical and structural properties of films formed when fresh Li reacts in gas environments, using X-ray Photoelectron Spectroscopy, Fourier-Transform Infrared Spectroscopy, electron microscopy and thermal/microstructural modeling; (2) Perform cycling measurements and quantify key electrochemical metrics of Coulombic efficiency, cycle life, and short-circuit time; (3) Measure the physical and electrochemical properties of the reactant gas, including reaction kinetics, transport parameters, and electrochemical activity within battery environments, which are relevant to SEI-healing processes; (4) Probe the feasibility and mechanisms of healing reactions using these gases. This effort will contribute new knowledge of how gas molecules decompose in far-from-equilibrium reactions at the surface of a Li electrode, and how this reactivity can be exploited to develop optimized interphases for improved efficiency and cycle life.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.