fig3

Figure 3. (A) Model of the layered structure with R$$\overline{3m}$$ space group. This figure is quoted with permission from Yu et al.^[2]. (B) Schematic for 180° superexchange interaction. This figure is quoted with permission from Zheng et al.^[26]. (C) Schematic diagram of magnetic frustration effect. This figure is quoted with permission from Li et al.^[25]. (D) Migration routes of Ni ions to Li sites in the layered structure for the Oh → Td → Oh route (i) and the Oh → V_O site → Oh route (ii), (E) Energy barriers calculated for migration of a Ni ion for the Oh → Td → Oh route (i) and the Oh → V_O site → Oh route (ii), the x-axis denotes the positions of Ni ions on the migration paths in (D). This figure is quoted with permission from Kim et al.^[52].