Fig. 3

Anionic reaction mechanism investigation of LFOx. a Raman spectra of LFOx in states of pristine (black), raw composite cathode (blue), initial cathode in in-situ cells (green), and charged cathode in in-situ cells (red). b Symmetric C–C stretching and asymmetric C = O stretching corresponding to I and II peaks as framed in (a). d In-situ Raman spectra of LFOx when cycled in the window 2.0–4.5 V as displayed in (c). The characteristic peaks between 800–900 and 1450–1550 cm⁻¹ are highlighted in the right hand column. f, g Evolution of carbon and oxygen synchrotron NEXAFS spectra corresponding to diverse states as dotted in the charge and discharge process in (e). All EXAFS are normalized. The bottom black lines in (f, g) are the reference composed of carbon conductor and additive in the same ratio as in composite cathode. Detailed assignments of peaks in (f, g) are stated in the main text