NMR and FT-IR Investigation of Spinel LiMn2O4 Cathode Prepared by the Tartaric Acid Gel Process

✍ Scribed by Y.M. Hon; H.Y. Chung; K.Z. Fung; M.H. Hon

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 404 KB
• Volume: 160
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9242

✦ Synopsis

The structure of the lithium manganese tartrate precursor and the synthesis mechanism of LiMn 2 O 4 were investigated by FT-IR, NMR, TG/DSC, and XRD in this study. The results of FT-IR and 7 Li and 13 C NMR measurements revealed that lithium ions bond with carboxylic acid ligands and the O}H stretching modes of tartaric acid. Manganese ion bonds only with carboxylic acid. Lithium and manganese ions were trapped homogeneously on an atomic scale throughout the precursor. Such a structure eliminates the need for long-range di4usion during the formation of lithium manganese oxides. Therefore, spinel LiMn 2 O 4 was synthesized at temperatures as low as 3003C. In this work, the electrochemical properties of Li/Li x Mn 2 O 4 were studied. It is clear that the discharge curves exhibit two pseudo plateaus as the LiMn 2 O 4 is 5red to higher temperatures. The discharge capacity of LiMn 2 O 4 increases from 84 to 117 mAh/g as the calcination temperature increases from 300 to 5003C. The LiMn 2 O 4 powders calcined at low temperatures with a high speci5c surface area and an average valence of manganese exhibit a better cycle life.