Figure 2

SEM images of LiNixMg0.08Mn1.92−xO4 samples (a) x = 0, (b) x = 0.01, (c) x = 0.03, (d) x = 0.05, (e) x = 0.08, (f) x = 0.10, (g) x = 0.12 and (h) x = 0.15, (i) TEM and (j) high-resolution transmission electron microscopy (HRTEM) images of LiNi0.03Mg0.08Mn1.89O4 sample, the inset is the corresponding selected area electron diffraction (SAED) pattern, (k–o) mapping analysis for Mn, O, Ni and Mg in the LiNi0.03Mg0.08Mn1.89O4 sample.