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

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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.