Collaborative Research: Creep-enabled 3D solid-state lithium metal batteries

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The development of all-solid-state rechargeable batteries based on lithium (Li) metal plating and stripping has highlighted a grand challenge: Li metal is chemically highly corrosive and mechanically stressful to the surrounding solid components, causing both electrochemical and mechanical instabilities. This project includes fundamental research to design a solid-state battery architecture in which Li metal functions as “a working fluid” rising and falling during electrochemical cycling with minimal electrochemical corrosion and mechanical stress generation. Insights from this project will potentially result in safer and higher density all-solid-state Li-metal batteries. Further, in this project a diverse group of students will be trained in a multidisciplinary setting and enhance underrepresented minority groups involvement and participation in science and engineering in general and mechanoelectrochemistry in particular at Penn State and MIT. Li metal is a soft crystal and exhibits either solid-like displacive behavior or fluid-like diffusive behavior. Li metal is also chemically aggressive, causing decomposition of solid electrolytes, consumption of active Li inventory, and uncontrollable growth of solid-electrolyte interphase. Li-metal anodes thus face stress-corrosion cracking under dual aggressive chemical and mechanical driving forces, making stable contact against Li metal challenging. To overcome these limitations, this project aims to construct a three-dimensional (3D) Li-metal host made of mixed ionic-electronic conductors (MIECs) and electronic and Li-ion insulators (ELIs). The project will develop design principles for the 3D MIEC/ELI based battery through integrated multi-faceted experimental characterization and multiscale computational modeling. Experimentally, in-situ transmission electron microscopy (TEM) will be carried out to directly observe Li deposition/stripping in the composite structure and scale up to battery-cell level testing. Computationally, molecular dynamics and multi-field continuum-level models will be coupled to simulate Li deposition/stripping and identify the dominant interfacial processes. Such an in-depth characterization and understanding will offer guidance to the optimization of the 3D MIEC/ELI based Li-metal batteries with improved cycling performance.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.