Influence of Co substitution and Cu addition on structural, electrical, transport and electrochemical properties of LixNi0.9 − yCoyMn0.1O2 cathode materials
Abstract LiNi1 − y − zCoyMnzO2 (y = 0.25, 0.35, 0.5, 0.6; z = 0.1, 0.2) cathode materials were synthesized by a soft chemistry, EDTA-based method. Among studied oxides, LiNi0.65Co0.25Mn0.1O2 compound possesses the best electrical conductivity. Higher amount of Mn in the samples worsen transport properties of these oxides. The observed decrease of the electrical conductivity of the compounds during deintercalation process can be correlated with a decrease of the effective charge carriers concentration. Additional, small Cu doping, realized for LiNi0.63Cu0.02Co0.25Mn0.1O2 composition, allows to retain high electrical conductivity during deintercalation process in this oxide, with relatively wide chemical stability range being from 1 to 0.35 mol of lithium. Additionally, in this paper the results of measurements of electrochemical performance of studied cathode materials are presented. During the first 10 cycles the best performance was observed for Li/Li+/LixNi0.63Cu0.02Co0.25Mn0.1O2 cell, which can be connected to the improved kinetics of the intercalation process related to a high lithium diffusivity in the cathode material.