Initiation of dendritic failure of LLZTO via sub-surface lithium deposition
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Featured on the front cover of Energy & Environmental Science (Vol 17 No 7 (2024)), this paper* co-authored by researchers from this department and The Faraday Institution, the James Watt School of Engineering and the Oxford Centre for Energy Materials Research (Henry Royce Institute) examines the occurrence of lithium deposition in occluded spaces within ceramic electrolytes due to electronic leakage currents which can jeopardise the commercialisation of power-dense solid-state batteries.
Plasma-FIB serial sectioning was utilised to visualise the surface and sub-surface of a garnet solid electrolyte (LLZTO) after lithium plating. The authors studied the morphology of surface spallation cracks, which represent the initial stage of dendrite formation. By employing a LiMg anode, the authors were able to track the magnesium diffusion around the surface cracks with EDS.
The absence of magnesium in early-stage cracks suggests that they form due to the pressure build-up from the deposition of pure lithium in occluded pores near the electrolyte surface. These spallation cracks act as current focusing and stress concentration hot spots. Electron beam induced current imaging demonstrates that short-circuiting lithium dendrites grow from the spallations during plating, and therefore the sub-surface deposition of lithium is a possible explanation for the initiation of lithium dendrites in LLZTO.
*'Initiation of dendritic failure of LLZTO via sub-surface lithium deposition'.
