Fig. 15. Contour map of operando XRD patterns during the initial charge/discharge process at 1.5–4.5 V of (a) NFM and (b) LNFMT. XANES (c) Ni K-edge and (d) Fe K-edge spectra of LNFMT during the first charge/discharge process. EXAFS (e) Ni K-edge and (f) Fe K-edge spectra of LNFMT during the first charge/discharge process. (g) First principles calculations of bonding energy changes after different degrees of Na⁺ de/intercalation. (a)–(g) are reprinted with permission from ref. 147. Copyright 2024 Elsevier.