Saturated linear dicarboxylic acids as chelating agents for the sol-gel synthesis of LiNi0.8CO0.2O2

A series of saturated aliphatic dicarboxylic acids have been studied as chelating agents for the synthesis of LiNi0.Co-8(0).O-2(2). The decomposition temperature of the dicarboxylate precursors was found to increase linearly with the number of -(CH2)- groups in the acid. From XRD analysis it was concluded that irrespective of the acid, the optimized heat treatment protocol for the synthesis of LiNi0.Co-8(0).(2)0(2) was calcination at 800 degreesC for 12 h. The product obtained from the adipate precursor gave the highest first-cycle capacity (178 mAh/g), while that from the suberic acid complex gave high capacity and cyclability. The effects of the solvent and pH of the precursor solution on the product characteristics are also discussed. Some related work on LiNi0.Co-8(0).O-2(2) prepared with maleic, oxalic and tartaric acids as complexing agents is also presented. (C) 2004 Elsevier B.V. All rights reserved.