Interface potentials inside solid-state batteries: Origins and implications

Interface resistance has become a significant bottleneck for solid-state batteries (SSBs). Most studies of interface resistance have focused on extrinsic mechanisms such as interface reactions and imperfect contact between electrodes and solid electrolytes. Interface potentials are an important intrinsic mechanism that is often ignored. Here, we highlight Kelvin probe force microscopy (KPFM) as a tool to image the local potential at interfaces inside SSBs, examining the existing literature and discussing challenges in interpretation. Drawing analogies with electron transport in metal/semiconductor interfaces, we showcase a formalism that predicts intrinsic ionic resistance based on the properties of the contacting phases, and we emphasize that future battery designs should start from material pairs with low intrinsic resistance. We conclude by outlining future directions in the study of interface potentials through both theory and experiment.

Automated summary

This article discusses the issue of interface resistance in solid-state batteries, highlighting the importance of interface potentials as an intrinsic mechanism that is often overlooked. By using Kelvin probe force microscopy to image the local potential at interfaces inside SSBs, the article examines the existing literature and discusses challenges in interpretation. Analogies with electron transport in metal/semiconductor interfaces are drawn to showcase a formalism that predicts intrinsic ionic resistance based on the properties of the contacting phases. The article concludes by outlining future directions in the study of interface potentials through both theory and experiment.