Extended Data Fig. 6: Example damage series profiles and initial/final spectra taken for lithium materials relevant to this study over a range of doses at which damage occurs, dark-field cryo-STEM images of various types of damage induced in a frozen organic electrolyte at different doses with corresponding spectra, and before and after images of the regions in which the EELS maps in the main text were taken.

All spectra were recorded at cryogenic temperatures. a, We found all oxide materials convert to Li₂O under large doses. Li₂O and LiH are primarily affected by mass loss, with no substantial changes in fine structure. The maps presented in the main text were acquired at doses lower than the dose indicated by the red arrows shown at the bottom of the plots, of the order of 10² e⁻ Å⁻². b, c, While some structural modification of the electrolyte material was present at low doses, probably due to liberation of hydrogen, a dose greater than 10³ e⁻ Å⁻² was required for substantial mass loss and modification of spectral fine structure. At 3 × 10³ e⁻ Å⁻², approximately 50% of the material remained after the map, as determined by the ADF signal. At 10⁴ e⁻ Å⁻², the material was completely removed in some areas, but the carbonate portion of the molecule remained. Doses applied during acquisition of the maps in the main text were less than the lowest dose shown here. Spectra are offset vertically for clarity. d, e, In the maps displayed in the main text, small structural changes were observed in the organic materials, which is expected given our damage analysis. This is probably due to liberation of hydrogen from the molecules, which occurs at low dose. The fine structure is not greatly affected until approximately an order of magnitude higher dose than was applied during these maps, which was of the order of 10² e⁻ Å⁻². Scale bars, 200 nm, 30 nm and 60 nm (b, left to right), 300 nm (d, e).