Elucidating Differences in Surface and Bulk Properties of Solid-State Electrolytes

Solid-state batteries with metal anodes are now widely recognized as the next frontier of battery research to satisfy the stringent requirements of safety, energy and power density for transportation and aviation applications. There is still a plethora of interfacial and chemomechanical challenges to be solved before these batteries achieve mass market adoption. These challenges include interface stability and dendrite growth, limits on stripping and plating current densities, and device integration [1]. These challenges warrant an investigation of the buried surfaces and interfaces present in solid-state batteries in the presence of electric fields encountered during battery operation. In this talk, I will discuss how the properties of surfaces and interfaces of solid-state batteries differ from the bulk using large scale simulations of defects based on first-principles and machine learning force fields. Our results confirm a high degree of atomic disorder at the interface, which effectively modulates the defect thermodynamics. Further, I will show how the mechanical stress at the interface affects these defects. These results have broad implications on ionic transport, charge transfer and rate capability, and dendrite growth in solid-state batteries through control of the properties of grain boundaries and interfaces. This work demonstrates the need for continuum models to be refined to account for the drastically different properties at the surfaces and interfaces.<br/><br/>[1] Ahmad, Z.; Venturi, V.; Sripad, S.; Viswanathan, V. Curr. Opin. Solid State Mater. Sci. 2022, 26, 101002.