Fig. 5: Comparison of Operando O K-edge XAS with various C=O containing reference compounds.

a FY-XAS of the O K-edge taken during cycling at different potentials ranging from OCV down to 0.05 V. Reference spectra of materials sharing the -C(=O)O- structural motif are also shown for comparison. b Excitation energies of the O 1s → π* transition for a number of molecules possessing an C=O bonding configuration and either two, one or no C-O bonds47,49,88,94,98,100,121,122,123,124,125,126,127,128,129,130,131,132. Peak positions from (a) are included in grey, and Li2O is also included in black for reference but doesn't correspond to the molecular motifs shown. See Supplementary Table S3 for further information on the data used here.