Durability Analysis of Li-O2 Batteries Through in-Situ μ-XRD Characterization

Using a microfocused synchrotron X-ray diffraction (μ-XRD) method, the formation of chemical species in lithium-air (Li-O₂) batteries was analyzed to understand the mechanism for cell deactivation at the anode and anode/separator interface, with a spatial resolution of 5 μm, while the Li-O₂ batteries were cycling (charging-discharging). The μ-XRD spectra demonstrated growth of same-sized LiOH crystals at the anode/separator interface during cycling, contributing to cell deactivation due to obstruction of Li⁺ ion transport and consumption of Li as the formation of LiOH occurred. Analysis of Li-O₂ cells with long-term cycling revealed the expansion of the LiOH layer due to pressure created during formation, which compresses the separator and cathode porous layers. Ultimately, this compression compromises pore structure used for Li⁺ ion and O₂ transportation, potentially contributing to cell deactivation. Analysis of the separator and cathode layers will provide further information into the causes behind cell deactivation, though results will be reported at a later date.