Li1−xAlx(Ni0.5Co0.2Mn0.3)1−yAlyO2 (NMCA) are synthesized by solid-state method.
LiAlO2 phase with high Li+ ion diffusivity appears in Li1−xAlxNi0.5Co0.2Mn0.3O2.
Al prefers to form AlO solid solution in Li(Ni0.5Co0.2Mn0.3)1−yAlyO2 samples.
AlO solid solution improve the structural stability of LiNi0.5Co0.2Mn0.3O2.
Substitution of Li with low Al content has superior advantages for NMCA.