Synthesis and electrochemical characteristics of spinel phase LiMn2O4-based cathode materials for lithium polymer batteries

Spinel LiMn2O4 and LiMn1.95Ni0.05O4 powders have been synthesized by a sol-gel method using an aqueous solution of metal acetates containing glycine. The dependence of the physicochemical properties of the spinel LiMn2O4 powders on the calcination temperature and glycine quantity have been extensively investigated. The porous LiMn2O4 and LiMn1.95N0.05O4 electrodes were electrochemically characterized by using charge/discharge experiments along with ac impedance spectroscopy. The LiMn1.95Ni0.05O4 electrode exhibited improved cycling performance in comparison with the stoichiometric LiMn2O4 one in spite of a small reduction in the initial capacity. The good capacity retention of the LiMn1.95Ni0.05O4 electrode is attributed to stabilization of the spinel structure by Ni doping for Mn ion sites and higher chemical diffusivity of lithium ions with cycling.