A new strategy to quickly synthetize true nanoparticles of the spinel LiMn2O4 by using a microwave-assisted hydrothermal route

Abstract

Based on a microwave-assisted hydrothermal reaction, a new route is proposed to prepare highly pure true nanoparticles (≤15 nm) of the single-phase spinel LiMn2O4 (LMO) at a low temperature (140 °C) and short reaction time (5 min), using exclusively water-soluble reagents. The obtention of this material was confirmed by using different techniques such as X-ray diffractometry, Rietveld crystal structure refinement, inductively coupled plasma-atomic emission spectroscopy and high-resolution transmission electron microscopy. Electrochemical evaluations were performed by using cyclic voltammetry and galvanostatic charge and discharge tests. Only electrodes prepared from spinel LMO nanoparticles with an average size of ~15 nm showed electrochemical activity. From charge and discharge tests at a constant rate of C/5, the electrodes prepared from this active material exhibited an initial specific capacity of 128 mA h g–1 with a capacity retention of 95% after the 27th cycle. The hallmark of the synthesis route here described is the saving of energy while preparing truly nanoparticulate LMO with excellent chemical, structural and promising electrochemical properties.