Fig. 3

Electronic structural evolution of antiphase boundaries and transition-metal ion migration front after delithiation. a Atomic scale HAADF-STEM image of antiphase boundaries with blue arrow showing the EELS line scan trajectory. b–d EELS spectrum of O, Mn, and Ni extracted from the line scan result of a. Light blue dashed line rectangle indicates the position of two antiphase boundaries in a. We can see the Mn edge shifts to left (lower energy) and Ni edge shifts to right (higher energy), which means the valence state of Mn decreased and Ni increased. e Element content results of EELS line scan of a, showing the content fluctuation of O, Mn, and Ni. The results show the O and Mn content decreased, Ni content increased at antiphase domain boundaries. g Atomic-scale structure of the migration-front area with a blue arrow indicates the EELS line scan trajectory. h, i, j EELS spectrum of O, Mn, and Ni from g. Light blue dash line rectangle indicates the position of the migration front in g. Due to the edge shift of Ni and Mn, the valence state of Mn decreased and Ni increased. f Element content results of EELS line scan of g shows that the Mn content decreased, while the Ni content increased, and O content remains mostly constant at the migration front. Scale bar, 5 nm