Interphase and Penetration Dynamics for Stable Alkali Metal Anodes

一个拥有可持续能源未来的繁荣社会依赖于先进的储能技术。虽然锂（Li）离子电池已经通过电子设备、便携式电动工具和电动汽车改变了人们的生活，但是进一步提高能量存储的技术水平一直是困难的。一种方法是用锂金属阳极的可吸收膜代替笨重的石墨阳极，以使电池的能量密度几乎加倍。然而，这种类型的电池材料在阳极上经受锂金属的指状树枝状生长的形成。 这些会生长到电解质和隔膜组件中，并导致电气短路，从而损坏电池并存在安全隐患。迫切需要抑制电气短路的根本原因，特别是在高电流密度下，当高容量下一代电池需要快速充电时。该基础研究项目致力于研究导致潜在短路和能量损失的组件缺陷（例如枝晶和电极涂层）的形成。该项目将产生新的理解，这将使电极的上级设计，这将导致更安全，高能量密度电池。该项目还将有利于研究生、本科生和K-12学生的教育。将建立一个暑期项目，目标是利用金属基电池的工程概念，针对代表性不足的高中年龄段的学生和高中教师。本研究的重点是锂，钠和钾金属阳极的界面和金属渗透动力学，调查（1）宏观电极-隔板不稳定性的动力学如何自然地选择几个不同的孔隙进行金属渗透，在低电流密度和面积容量下，与沉积的均匀性无关;（2）在所选孔中的实际金属生长机制;以及（3）SEI微结构的原位形成动力学以及对（1）和（2）中的宏观和微观动力学的影响。这是第一次研究，以建立一个定量的了解，孔隙选择和孔内生长动态过程中碱金属渗透通过多孔隔板。独特的透明毛细管细胞将在光学显微镜下进行操作性监测。先进的表征和成像技术在原子和纳米尺度，如低温透射电子显微镜，将用于确认的特征长度的SEI微观结构在横向方向。通过紧密结合的实验和理论研究，将开发一个新的理论框架，可以无缝连接的领域实验，以指导稳定的碱金属阳极的整体设计。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

A prosperous society with a sustainable energy future relies on advanced energy storage technologies. While lithium (Li)-ion batteries have changed lives through electronic devices, portable power tools and electric cars, further increasing the state of the art for energy storage has been difficult. One approach is to replace the bulky graphite anode with an ultrathin film of Li metal anode to nearly double the energy density of the battery. However, this type of battery material is subjected to formation of finger-like dendritic growths of lithium metal on the anode. These can grow into the electrolyte and separator components and cause an electrical short circuit that can destroy the battery and present a safety hazard. Suppressing this root cause of electrical short circuits is an urgent need, especially at higher current densities when fast recharge is required for high-capacity next-generation batteries. This fundamental research project addresses the study of formation of the component flaws (e.g. the dendrites and electrode coatings) that cause a potential short circuit and also loss in energy capacity. This project will generate new understanding that will enable superior designs of electrodes that will lead to safer, high energy density batteries. The project will also benefit the education of graduate, undergraduate and K-12 students. A summer program will be establish that will target underrepresented high school age students and high school teachers using engineering concepts of metal-based batteries.This study focuses on the interphase and metal penetration dynamics of lithium, sodium, and potassium metal anodes, investigating (1) how the dynamics of the macroscopic electrode-separator instability will naturally select just a few disparate pores for metal penetration, at low current densities and areal capacities, regardless of the uniformity of deposition; (2) the actual metal growth mechanisms in the selected pores; and (3) the in situ formation dynamics of the SEI microstructures and the impact on the macroscopic and microscopic dynamics in (1) and (2). It is intended to be the first study to establish a quantitative understanding of pore-selection and in-pore growth dynamics during alkali metal penetration through porous separators. Unique transparent capillary cells will be monitored operando under optical microscope. Advanced characterization and imaging technologies at atomic and nanoscales, such as cryo-transmission electron microscopy, will be used to confirm the characteristic lengths of SEI microstructures in the lateral direction. Through the intimately combined experimental and theoretical investigation, a new theoretical framework that can seamlessly connect the domain experiments will be developed to guide the holistic design of stable alkali metal anodes.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.