Fig. 3: Fluorine increment of the anodes through thermal storage.

a–c Top-view SEM images and EDS elemental maps of graphite/SiO anode a before and b after 4 weeks of HT storage and c corresponding relative atomic ratios of fluorine. d Cross-sectional SEM images and line scan profiles of graphite/SiO anode after HT storage. e, f SEM images and EDS elemental maps of graphite/SiO anode e before and f after 4 weeks of HT storage.