Fig. 1: Local structures and diffusion barriers for elemental dopants in LMO.
From: Entropy-increased LiMn2O4-based positive electrodes for fast-charging lithium metal batteries
a Schematic illustrations of undoped and V, Cr, Al-doped LMO structure showing small changes, Ti-doped LMO structure showing expansion, and Cu, Fe, Mg, Ni, Zn-doped LMO structure showing contraction. The cyan, navy blue, emerald green, red, and sandy-brown spheres symbolize Li, Mn, and their equivalent metals (V, Cr, Al), a high-valence metal (Ti), low-valence metals (Cu, Fe, Mg, Ni, Zn) and O atoms, respectively. The shadows surrounding each sphere illustrate the varying electron localization capabilities among these different types of atoms. b–d 2D slices of electron localization function (ELF) of valence electrons viewed along the (100) lattice planes of b LMO, c Ti-LMO, d Cu-LMO, respectively. The numbers on the ELF contours are the calculated Bader charge values of O, Mn, Cu and Ti. e, f Impact of the M-O bond length on e Li-O distances and f Mn-O bond lengths in the ten structurally optimized LMO with different substituted cations, including Cu, Fe, Mg, Ni, Zn-doped LMO (red squares and spots), Ti-LMO (emerald green square and spot), and LMO doped with Mn, V, Cr, and Al (navy blue squares and spots). g–i Diffusion paths and Li-O bond length changes in g LMO, h Ti-LMO, and i Cu-LMO, respectively. The marked numbers are the bond length in Å. j Diffusion barriers of tetrahedron (8a)-octahedron (16c)-tetrahedron (8a) paths in LMO, Ti-LMO and Cu-LMO.
