fig6

Figure 6. (A) High angle annular dark field scanning transmission electron microscope (HAADF-STEM) images of P2/Li-O3 sample; (B) Structural evolution of P2/Li-O3 during the first charge/discharge process in comparison with pure P2 cathode. Reproduced with permission, Copyright 2022^[106], Elsevier B.V.; (C) Normalized composition of Ni, Fe, and Mn in selected particles of P2/O3 and P2 materials; (D) Calculated cationic potentials and formation energies rationalizing the structure-composition relationship; (E) In situ XRD revealing the structural evolution of P2/O3 cathode; (F) Electrochemical performance of O3, P2, and P2/O3 cathodes. Reproduced with permission, Copyright 2022^[114], Elsevier B.V.; (G) Schematic illustration of structural evolution driven by Mg substitution contents in Na_0.6Mn_1-xMg_xO₂ (x = 0.05, 0.1); (H) Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution (HR-TEM) images with corresponding fast Fourier transform (FFT) electron diffraction (ED) patterns of P2/tunnel Na_0.6Mn_0.95Mg_0.05O₂; (I) Long-cycling stability of the P2/tunnel cathode; (J) Structural evolution of the P2/tunnel cathode revealed in situ XRD patterns. Reproduced with permission, Copyright 2023^[120], Wiley-VCH; (K) Schematic diagram of the formation conditions of mixed-phase materials; (L) Electrochemical performance of the P3/P2/O3 tri-phase cathode compared to biphasic P3/P2 and P2/O3 materials. Reproduced with permission, Copyright 2022^[124], Wiley-VCH.