Phase transition of Li_xNi_0.8Co_0.15Al_0.05O₂charged cathode during heating: (a) layered structure, (b) cation migration during the phase transition from layered structure to disordered-spinel structure, (c) disordered spinel structure, and (d) cation migration path from octahedral A to octahedral B. Direct migration (path 2) between octahedral sites is energetically unfavorable, so transition metal ions prefer to travel through a neighboring tetrahedral site to the octahedral site (path 1).^[31]