[en] Highlights: • The content of Ni"2"+ in the Li layer decreases with the Li-excess increase in Li_1_+_xNi_0_._5Co_0_._2Mn_0_._3O_2 (x = 0, 0.02, 0.04, 0.06, 0.08) materials. • Li_1_._0_8Ni_0_._5Co_0_._2Mn_0_._3O_2 has the largest diffusivity value in all samples. - Abstract: Layered Li_1_+_xNi_0_._5Co_0_._2Mn_0_._3O_2 (x = 0, 0.02, 0.04, 0.06, 0.08) materials were synthesized using the co-precipitation method. Rietveld refinements measurements reveal that the concentration of Ni"2"+-3b ions decreases from 0.06 to 0.043, with x changing from 0.02 to 0.08. The initial coulombic efficiency improves with the increase in the content of Li-excess because the content of Ni at the 3b site decreases with the increase of Li-excess in the samples from 0 to 0.08. The analysis indicates that Li_1_._0_8Ni_0_._5Co_0_._2Mn_0_._3O_2 exhibits the largest diffusivity value due to the dependence of the diffusion coefficient of lithium ions on the content of Ni in the 3b sites