Nanostructured Lithium Manganese Oxide Cathodes Obtained by Reducing Lithium Permanganate with Methanol

Abstract

Reduction of lithium permanganate with methanol in acetonitrile and acetonitrile-water media has been investigated to obtain nanocrystalline lithium manganese oxides. The products have been characterized by wet-chemical analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and transmission electron microscopy. The samples synthesized in acetonitrile medium consist of a considerable amount of organic residue even after firing at 250°C in vacuum, which could be lowered by introducing water into the synthesis and washing media (acetonitrile-water mixture). Additionally, introduction of lithium hydroxide into the synthesis medium helps to increase the lithium content and Li/Mn ratio in the product and thereby to improve the electrochemical performance. Optimum compositions synthesized in the acetonitrile-water medium exhibit capacities of >200>200 mAh/g with good cyclability and charge efficiency. © 2002 The Electrochemical Society. All rights reserved.