CAREER: Designing Interfaces for Electrochemical Energy Storage: A Mechanistic Perspective

这个CAREER项目的重点是锂硫（li -硫）电池，它有望在下一代储能系统中实现更低的成本和更高的容量。用于汽车和储能的先进锂电池可以提高国内能源安全，但其使用主要受到电极/电解质界面不良化学副反应的限制。该项目旨在从根本上了解电池运行过程中该界面的反应。这种基本的理解将有助于解决电池稳定性和整体电池性能的问题。与该项目相关的教育和推广活动是(i)为高中生和中学生提供实践经验，（ii）让本科生参与尖端研究活动，重点是让代表性不足的学生参与STEM， （iii）为研究生提供创新和创业机会。虽然锂硫电池已被广泛探索，但固/液电解质界面多硫氧化还原反应机制的许多方面仍不清楚。在缺乏详细的机械理解的情况下，电极结构的合理设计一直是困难的。该项目的技术目标是通过使用原位扫描电化学显微镜方法结合拉曼光谱（SECM-Raman），绘制Li-S电池充放电过程中多硫化物形态的时空演变图。该研究计划以两个指导性假设为基础；(1)测量界面性质将允许（电）化学反应途径的机理阐明，并提供多硫化物溶解-歧化-沉淀动力学的信息；(2)阐明反应机制将控制电化学界面，从而用适当的材料设计多硫化物穿梭。该项目的成功完成预计将：(i)使用一种新的分析工具，以高时空分辨率在纳米尺度上增强对电极/电解质界面相互作用的基本理解；（ii）以高时间分辨率绘制瞬态条件下多硫化物与电极表面和电解质溶剂的相互作用图。（iii）确定催化剂的作用和整个多硫化物氧化还原过程中的限速步骤，以评估锂硫电池材料的优越性能。由此产生的硫（电）化学反应在界面上发生的机理解释将为Li-S氧化还原化学提供新的见解，并将允许详细绘制多硫化物穿梭体的时空演变；Li-S系统的核心问题。

This CAREER project focuses on lithium-sulfur (Li-S) batteries, which promise lower cost and higher capacity in next-generation energy storage systems. Advanced lithium batteries for vehicles and energy storage could improve domestic energy security, but their use is mainly limited by undesirable chemical side reactions at the electrode/electrolyte interface. This project seeks to fundamentally understand the reactions at this interface during battery operation. This fundamental understanding will help resolve the issues of battery stability and overall battery performance. The education and outreach activities associated with this project are to (i) provide hands-on experience to high school students and middle school students, (ii) engage undergraduate students in cutting-edge research activities with strong emphasis on the involvement of underrepresented students in STEM and (iii) provide innovation and entrepreneurship exposure to graduate students.While Li-S batteries have been extensively explored, many aspects of the mechanisms of polysulfide redox reactions at solid/liquid electrolyte interfaces remain unclear. In the absence of detailed mechanistic understanding, rational design of electrode architectures has been difficult. The technical objective of this project is to map the temporal and spatial evolution of polysulfide speciation during the charge/discharge process in a Li-S battery through use of in-situ scanning electrochemical microscopy methods coupled with Raman spectroscopy (SECM-Raman). The research program is underpinned by two guiding hypotheses; (1) measuring interfacial properties will allow for mechanistic elucidation of (electro)chemical reaction pathways and provide information on kinetics of polysulfide dissolution-disproportionation-precipitation and (2) elucidating the reaction mechanism will control the electrochemical interface and thereby polysulfide-shuttle with an appropriate material design. The successful completion of the project is expected to (i) enhance fundamental understanding of interactions at the electrode/electrolyte interface at the nanoscale level with high spatiotemporal resolution using a new analytical tool, (ii) map the interaction of polysulfides with the electrode surface and with electrolyte solvents under transient conditions with a high temporal resolution, and (iii) define the role of catalysts and the rate-limiting step in the overall polysulfide redox process to assess superior performance of materials for Li-S batteries. The resulting mechanistic elucidation of sulfur (electro)chemical reactions occurring at the interfaces will provide new insight into Li-S redox chemistry and will allow for detailed mapping of the spatial and temporal evolution of the polysulfide shuttle; a core issue in the Li-S system.