Imaging Sodium Dendrite Growth in All-Solid-State Sodium Batteries Using 23Na T2-Weighted Magnetic Resonance Imaging

Two-dimensional, Knight-shifted, T-2-contrasted Na-23 magnetic resonance imaging (MRI) of an all-solid-state cell with a Na electrode and a ceramic electrolyte is employed to directly observe Na microstructural growth. A spalling dendritic morphology is observed and confirmed by more conventional post-mortem analysis; X-ray tomography and scanning electron microscopy. A significantly larger Na-23 T-2 for the dendritic growth, compared with the bulk metal electrode, is attributed to increased sodium ion mobility in the dendrite. Na-23 T-2-contrast MRI of metallic sodium offers a clear, routine method for observing and isolating microstructural growths and can supplement the current suite of techniques utilised to analyse dendritic growth in all-solid-state cells.

Automated summary

This study utilized Na-23 MRI to directly observe the microstructural growth of sodium in an all-solid-state cell, revealing a porous dendritic morphology which was confirmed through various methods. The significantly larger T-2 contrast for dendritic growth compared to bulk metal electrode is attributed to increased sodium ion mobility within the dendrite. Na-23 T-2 contrast MRI of metallic sodium provides a clear and routine method for observing and isolating microstructural growth, complementing current techniques for analyzing dendritic growth in all-solid-state cells.