Collaborative Research: Fundamental understanding of interface dynamics in solid electrolyte batteries with liquid metal anode

固态锂离子电池（LIB）提供了一种更安全的替代品，因为与溶剂泄漏和易燃性相关的安全风险很大。这种电池甚至可以通过减少额外安全功能的必要性来支持更小，更强大的电池组。然而，尽管这些高离子传导性固体电解质具有益处，但实现与液体电解质LIB相当的比容量、倍率性能和循环寿命仍然具有挑战性。研究表明，一个主要的障碍是固体电解质和固体电极之间的界面不充分。首先，液体电解质中的液-固界面允许完全的电极渗透，从而促进锂离子在活性材料颗粒表面上的全面传输。为了利用固态电池中液固界面的好处，研究小组提出了从固-固界面到液-固界面的过渡。这可以通过在固态LIB内用液态金属电极代替固态电极来实现。在锂离子插入和移出的过程中，由于液态和固态之间的转变，电极-电解质界面和液态金属颗粒的内部都经历连续的变化。了解这些动态变化对于充分研究液态金属固体电解质LIB的潜力至关重要。本项目的目标是获得一个基本的了解之间的界面动力学的液体金属阳极和固体电解质在锂离子插入和移除过程。该项目将培养一个多元化和包容性的团队，包括研究生，本科生，学前班学生和K-12教师，特别强调鼓励代表性不足的人口的参与。该项目旨在为学生提供跨学科的培训，弥合理论理解和实验之间的差距。在该项目中，团队提出了一种创新的方法来研究新型固体电解质LIB，首次利用液态金属电极和固体电解质，在室温下形成液-固界面。他们的目标是了解在锂离子插入和移除过程中，这种液-固界面和固-固界面之间的过渡是如何发生的。从这项研究中获得的见解将促进在固体电解质电池中加入液态金属电极的新技术的发展。该团队将利用原位和操作聚焦离子束扫描电子显微镜（FIB-SEM）来分析形态的动态变化，并监测循环过程中液态金属颗粒中液固反应前沿的进展。此外，研究人员的目标是通过研究通过操作X射线衍射（XRD）获得的动态相变来研究掺杂剂的影响。为了了解锂离子插入和移除期间应力和应变的发展，沿着其对液态金属颗粒内相和形态的影响，基于相场模型的数值模拟，结合流体-结构相互作用、电化学反应、物质扩散和界面效应，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。

Solid-state lithium-ion batteries (LIBs) present a safer alternative to their commercially available counterparts that utilize liquid electrolytes, due to the substantial safety risks associated with solvent leakage and flammability. Such batteries could even support smaller and more powerful battery packs by diminishing the necessity for extra safety features. However, despite the benefits of these highly ionic conductive solid electrolytes, achieving comparable specific capacity, rate capability, and cycle life to that of liquid electrolyte LIBs remains challenging. Research indicates a major obstacle being inadequate interfacing between solid electrolytes and solid electrodes. Contrarily, the liquid-solid interface in liquid electrolytes permits full electrode infiltration, fostering comprehensive lithium-ion transport across the surface of active material particles. To leverage the benefits of the liquid-solid interface in solid-state batteries, the research team proposes a transition from the solid-solid interface to a liquid-solid interface. This could be achieved by replacing the solid electrode with a liquid metal electrode within solid-state LIBs. During the processes of lithium-ion insertion and removal, both the electrode-electrolyte interface and the interior of the liquid metal particle experience continuous alterations due to the shift between liquid and solid states. It is essential to understand these dynamic changes to fully investigate the potential of liquid metal solid electrolyte LIBs. The objective of this project is to gain a fundamental understanding of the interface dynamics between the liquid metal anode and the solid electrolyte during lithium-ion insertion and removal processes. The project will cultivate a diverse and inclusive team, encompassing graduate students, undergraduate students, precollege students, and K-12 teachers, with special emphasis on encouraging the participation of underrepresented populations. The project aims to provide interdisciplinary training to students, bridging the gap between theoretical understanding and experimentation.In this project, the team proposes an innovative approach to study a novel solid electrolyte LIB, the first to utilize a liquid metal electrode and a solid electrolyte, forming a liquid-solid interface at room temperature. Their objective is to understand how the transition between this liquid-solid interface and the solid-solid interface occurs during lithium-ion insertion and removal processes. Insight gained from this investigation will foster the development of new techniques that incorporate liquid metal electrodes in solid electrolyte batteries. The team will utilize in situ and operando focused ion beam-scanning electron microscopy (FIB-SEM) to analyze dynamic changes in morphology and monitor the advancement of the liquid-solid reaction front in liquid metal particles during cycling processes. Furthermore, the researchers aim to investigate the influence of dopants by studying dynamic phase changes obtained through operando X-ray diffraction (XRD). To understand the development of stress and strain, along with its effect on phases and morphologies within a liquid metal particle during lithium-ion insertion and removal, numerical simulations based on a phase field model, incorporating fluid-structure interaction, electrochemical reaction, species diffusion, and interfacial effects, will be conducted.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.