Effects of chromium on the structural, surface chemistry and electrochemical of layered LiNi0.8−xCo0.1Mn0.1CrxO2

Single phase LiNi0.8−xCo0.1Mn0.1CrxO2 (x = 0, 0.01, 0.02, and 0.03) compounds have been prepared by fast co-precipitation and anneal method. Electrochemical tests show that the sample b, with 1% Cr content, exhibits the highest discharge capacity, enhanced rate ability and cycling property among all samples. From the combination of Rietveld refinements, ICP, EDAX and XPS studies, it is supposed that the electrochemical improvement may be related to the suppressed cation mixing degree and reduced surface concentration of Ni ions, caused by Cr substitution. However, excess Cr substitution could also result in the appearance of Cr6+ and Mn3+ ions, which are mainly responsible for the capacity fading of positive materials. Therefore, Cr substitution should be controlled in reasonable range.