Abstract
The variations of structure and electrochemical properties of Li1-xNi1-yMnyO2 (y=0 and 0.2) were studied as lithium was deintercalated from the materials. The LiNi1-yMnyO2 was prepared by easily available LiOH, Ni(OH)2 and γ-MnOOH under air flow. Exchange of nickel into the lithium site (3(a)site) made it difficult for the lithium ion to move through the lithium layer, and decreased the electrical capacity for cyclic charge/discharge. Partial substitution of manganese for nickel was effective in preventing abrupt changes of the lattice constant c and Ni-O distances as x increases, resulting in suppressing the phase transitions (hexagonal→monoclinic→hexagonal). XPS, XANES and ESR analyses suggested that the charge compensation in charge/discharge of Li1-xNi0.8Mn0.2O2 could be attributed to changing valences of nickel.
