7li Chemical Shift Imaging to Detect Microstructural Growth in All Solid-State Batteries

Abstract

All solid-state batteries potentially offer safe, high energy density electrochemical energy storage, yet are plagued with issues surrounding Li microstructural growth and subsequent cell death. We use 7Li magnetic resonance chemical shift imaging and electron microscopy to track Li microstructural growth in the garnet solid-electrolyte, Li6.5La3Zr1.5Ta0.5O12. Here, we follow the early stages of Li microstructural growth during electrochemical cycling – from the formation of Li on the electrode surface to dendritic Li connecting both electrodes in a symmetrical cell and correlate these changes with electrochemistry (e.g. short circuiting). During these experiments, we observe changes at both the stripping and plating interfaces during Li microstructural growth, indicating heterogeneities in both Li removal and deposition. At low current densities, 7Li MRI detects the formation of Li microstructures in cells before obvious electrochemical signatures indicating their presence are observed.