Nanocrystalline and long cycling LiMn2O4 cathode material derived by a solution combustion method for lithium ion batteries

A nanostructured LiMn2O4 spinel phase is used as a cathode for 4 V lithium batteries and is prepared by solution combustion synthesis using urea as a fuel. Lithium–manganese oxides have received more increasing attention in recent years as high-capacity intercalation cathodes for rechargeable lithium-ion batteries. Nanostructured electrodes have been shown to enhance the cell cyclability. For optimum synthesis, the spinel LiMn2O4 showed that the optimal heat treatment protocol was a 10 h calcination at 700 °C, which sustained 229 cycles between 3.0 and 4.3 V at a charge–discharge rate of 0.1 °C before reaching an 80% charge retention cut-off value. X-ray diffraction and electron diffraction pattern investigations demonstrate that all the LiMn2O4 products are a spinel phase crystal. TEM micrographs show the prepared products were highly crystalline with an average particle size of 20–50 nm. Cyclic voltammetry shows the absence of phase transitions in the samples ensures negligible strain, resulting in a longer cycle life. This work shows the feasibility of the solution combustion method for obtaining manganese oxides with nano-architecture and high cyclability, and suggests it is a promising method for providing small diffusion pathways that improve lithium-ion intercalation kinetics and minimize surface distortions during cycling.