Iron-Gold Coated-LiMn<sub>2-X</sub>O<sub>4</sub> Nanowire High Power Cathode System Probed by Spectroscopic and Microstructural Analysis

Abstract

The migration of lithium (Li) ions in electrode materials affects the rate performance of rechargeable Li ion batteries. Therefore, the application of LiMn2O4, whichis an appealing cathode material in high power systems, requires fast electron transfer kinetics which is possible through the use of nanostructured morphologies and conductive material. Nanowires offer the advantage of a large surface to volume ratio, efficient electron conducting pathways and facile strain relaxation. In this study, LiMn2O4 nanowires with cubic spinel structure were synthesized by using a α-MnO2 nanowire-template-based method. LiMn2O4 nanowires have diameters less than 10 nm and lengths of several micrometers. Fe-Au nanoparticles were synthesized and used as coating material to improve both the catalytic activities and stability of the LiMn2O4 nanowires. The Li[Fe0.02Au0.01]Mn1.97O4 nanowires with modified architecture effectively accommodates the structural transformation during Li+ ion charge and discharge. Hence, the Li[Fe0.02Au0.01]Mn1.97O4 nanowire cathode system shows outstanding stability and enhanced electrocatalytical properties. Microstructural analysis of Li[Fe0.02Au0.01]Mn1.97O4 linked its composition and processing to its properties and performance. High resolution transmission electron microscope (HR-TEM) of the nanomaterial showed good crystallinity which contributed towards good reversibility. XRD analysis revealed a pure cubic spinel structure without any impurities. Structural information provided by Raman and solid state spectroscopy further corroborated these findings. The improved rate and cycling performance is related to the conductive particles infused within the nanowires which make up the electrode.