The mechanism of Sol-Gel synthesis of normal spinel LiMn2O4 with chelation of citric acid

• Published in: Journal of Wuhan University of Technology. Materials science edition Vol. 17; no. 4; pp. 21 - 24
• Main Authors: Hui, Wu, Jia-heng, Lei, Yong-xi, Chen, Yu-bin, Sun, Qi-hua, Yuan
• Format: Journal Article
• Language: English
• Published: Wuhan Springer Nature B.V 01.12.2002; Wuhan University of Technology
• Subjects: Acids; Cations; Chelates; Chelation; Citric acid; Condensates; Crystallization; Differential thermal analysis; Esterification; Homogeneity; Lithium manganese oxides; Manganese ions; Metal ions; Reaction mechanisms; Sol-gel processes; Spinel; Stoichiometry; sol-gel process; mechanism of reaction; chelation of citric acid; LiMn2O4
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/BF02838409

The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn^sub 2^O^sub 4^ and the reaction mechanism were investigated by means of XRD, IR, TG-DTA and SEM. The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed, and then with heating the esterification and condensation reactions occured between them and glycol. The products obtained are polymers in which metal cations are distributed homogenously on atomic scale that ensure high reactivity to cations of Li^sup +^ and Mn^sup 2+^. Firing the gel prepared by this process, the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided. At 400°C phase-pure LiMn^sub 2^O^sub 4^ with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained. The model of chelate coordinate of double-molecule between citric acid and Mn^sup 2+^ in the gel network is proposed. It is important for explaining the dispersion state of Mn^sup 2+^ and the formation process of gel by this model.[PUBLICATION ABSTRACT]