The Intersection of Cryo, Laser Ablation, and Nanoscale Electron Imaging for Intact Battery Characterization

Characterization of intact batteries is challenging due to the great diversity of the component materials. For example, lithium anode batteries contain a stack consisting of a metal current collector, the lithium metal anode, a polymer separator saturated with lithium salts in an aprotic electrolyte, a transition metal oxide cathode, and another metal current collector. These components are generally stacked within a spring-loaded coin cell for electrochemical performance testing of the cell for repeated charge and discharge cycling. General characterization techniques require the disassembly of the stainless-steel coin cell, with analysis of each of the components individually. Here, we present a method for retaining the internal structure of the coin cell by cryogenic plunge freezing of the entire stack, followed by in-situ, athermal, ultrashort-pulse laser ablation to access the internal components in cross-section, followed by standard characterization using scanning electron microscopy and energy dispersive x-ray spectroscopy. This provides the complete structural and compositional analysis of the intact battery stack with nanometer resolution, where we have determined several failure modes of lithium metal anodes for use as rechargeable batteries.