fig7

Figure 7. (A) Na-layer interplanar spacing evolution in substituted samples. (B) Structural modification of NM host via Fe/Ti co-doping. (C) Contour plots of principal diffraction peaks. (D and E) Lattice parameter variation during charging. (F) Cycling stability of NFMT/HC full cell. (A-F) Reproduced with permission^[137]. Copyright 2023, American Chemical Society. (G) Crystal structures of NaNMO and NaK_0.01NMTi_0.1O. (H) Na⁺ vacancy formation energies and 500-cycle performance of full cells at 1 C within 1.5-4.0 V. (I) The full cell assembled with a hard carbon anode showcases robust long-term cycling and high-capacity characteristics. (G-I) Reproduced with permission^[139]. Copyright 2023, Wiley-VCH GmbH. NM: Na_xTMO₂; NFMT: O3-Na_0.95Ni_0.40Fe_0.15Mn_0.3Ti_0.15O₂; HC: hard carbon.