A Nanoscale view of Solid-State Batteries

The demand for safe energy storage with high energy density is growing and as lithium-ion batteries are nearing their performance limits, solid-state batteries have emerged as promising successors. Solid-state batteries offer higher energy density, enhanced safety, and faster charge rates. However, their commercialization remains constrained by solid/solid interface processes, including metal filament formation, chemically or mechanically unstable electrolyte/electrode interfaces, and inhomogeneous cathodic reactions. Advanced nanoscale characterization techniques are essential for unveiling the mechanistic origins of solid-state battery degradation and performing real-time monitoring of nanoscale changes within battery materials, which reveal critical insights into dynamic interfacial processes under operational conditions. Such knowledge may unlock the full potential of solid-state batteries by guiding the development of new materials, battery architectures, and microstructures for improved performance and durability. This review surveys research on solid-state battery materials and components and examines how various nanoscale characterization techniques can diagnose and mitigate degradational phenomena in these electrochemical devices. We review recent studies examining different solid-state processes in solid-state batteries with a particular focus on the growth of filaments, metal deposition and secondary phase formation at the electrolyte/anode interface, interdiffusion and parasitic reactions at electrolyte/cathode interface, uneven cathodic reactions, mechanical failure of the electrodes, unwanted electronic leakage, and grain boundary heterogeneities within the electrolyte. Lastly, we describe future method developments enabling a deeper insight into the operation and degradation of solid-state batteries.