Understanding the Impact of Mechanical Constraints on the Dendrite Formation in Lithium Metal Anodes

金属锂因其高比容量、低密度和负电化学电位而成为锂离子电池负极材料中最具吸引力的材料之一。在锂/空气或锂/硫电池中使用锂金属可以获得比现有锂离子电池高出数倍的理论比能量，这可以推动基于锂离子电池的应用的技术创新，如便携式电子产品、电动汽车和储能系统。然而，锂在充放电循环过程中的枝晶锂生长对锂金属阳极电池构成了重大的安全挑战。在这个项目中，通过在锂离子电池中插入额外的硬质层作为机械约束来抑制树枝状锂的生长。该项目将从根本上提高对机械变形和锂枝晶生长之间关系的理解。新一代劳动力将接受使用最先进的计算工具进行计算力学和电化学之间的多学科研究的培训。储能材料特性和建模方面的新课程内容将整合到本科和研究生课程中，并将创建动手活动，向高中生传授各种与能源相关的主题。该项目的研究目标是使用新的计算建模框架，从根本上了解机械变形对锂树枝晶形成的作用。这个框架包括一个交错的优化方案，以解释在机械约束下锂树枝晶形成过程中不断变化的锂阳极几何形状和各种多物理效应。由此产生的相图将为实验者提供关于树枝晶行为的新见解，以定制材料属性和细胞设计以抑制树枝晶。这项研究将解开枝晶界面上电化学、热和力学行为之间的复杂耦合。它将回答许多基本问题，例如树枝晶是否会通过穿孔或刺穿来穿透分离器，力学如何改变树枝晶附近的电化学性质，或者力学如何改变树枝晶形态。最终，这项工作将向实验者提供反馈，以设计界面设计和结构设计，以实现更好、更安全的锂金属阳极。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Lithium metal is one of the most appealing anode materials for lithium-ion batteries due to its high specific capacity and its low density and negative electrochemical potential. Utilizing lithium metal in lithium/air or lithium/sulfur batteries can achieve a theoretical specific energy several times higher than in existing lithium-ion batteries, which could boost technology innovations of lithium-ion batteries based applications such as portable electronics, electric vehicles, and energy storage systems. However, dendritic lithium growth during charge/discharge cycles poses a major safety challenge to cells made with lithium metal anodes. In this project, dendritic lithium growth is suppressed by inserting an extra stiff layer in lithium-ion batteries acting as a mechanical constraint. The project will fundamentally improve the understanding of the relationship between mechanical deformation and lithium dendrite growth. New generation workforce will be trained in the use of state-of-art computational tools to conduct multidisciplinary research at the interface between computational mechanics and electrochemistry. New course contents on energy storage material properties and modeling aspects will be integrated into undergraduate and graduate courses and hands-on activities will be created to teach high school students various energy-related topics.The research goal of this project is to fundamentally understand the role of mechanical deformation on lithium dendrite formation using a new computational modeling framework. This framework includes a staggered optimization scheme to account for an evolving lithium anode geometry and various multiphysics effects during lithium dendrite formation under mechanical constraints. Resulting phase diagrams will provide experimentalists new insights on the dendrite behavior to tailor material properties and cell design to suppress dendrites. The research will untangle the complex coupling between electrochemical, thermal, and mechanical behaviors at dendrite interfaces. It will answer many fundamental questions such as whether or not dendrites will penetrate the separator by passing through its pores or by piercing it, how mechanics changes the electrochemical properties at the vicinity of dendrites, or how mechanics is changing dendrite morphologies. Ultimately, this work will provide feedback to experimentalists to engineer interface designs and structural designs for better and safer lithium 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.