Determining depth-resolved spatial distribution of solid–electrolyte interphase using non-destructive angle-resolved X-ray photoelectron spectroscopy for lithium-metal batteries

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The solid electrolyte interphase is a key performance regulator in Li-metal batteries, which are regarded as an important technology for future energy storage. Understanding this crucial interphase through non-destructive analysis is essential to advance the performance and lifespan of Li-metal batteries. We introduce angle-resolved X-ray photoelectron spectroscopy as a non-destructive technique for the depth-profile analysis of the solid electrolyte interphase in Li-metal batteries. Importantly, we show that this characterization technique displays a distinct advantage in preserving the solid electrolyte interphase's integrity compared to traditional sputtering-based depth-profiling. Our findings add to the understanding of compositional differences in the solid electrolyte interphase before the onset of Li electrodeposition and after Li plating. Moreover, we find significant variations in the thickness and distribution of solid electrolyte interphase species across different classes of electrolytes, which strongly influence the solid electrolyte interphase's protective properties and, by extension, Li-metal battery performance. This study benchmarks the application of angle-resolved X-ray photoelectron spectroscopy in revealing detailed, depth-resolved chemical composition of the solid electrolyte interphase in a non-destructive approach. Understanding the solid–electrolyte interphase formed on lithium is vital for improving the lifetime of lithium metal batteries. Here, authors show that angle-resolved X-ray photoelectron spectroscopy can reveal the depth-dependent composition of the interfacial layer without damaging it by ion sputtering.