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

Spinel LiMn 2 O 4 and LiMn 1.95 Ni 0.05 O 4 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 LiMn 2 O 4 powders on the calcination temperature and glycine quantity have been extensively investigated. The porous LiMn 2 O 4 and LiMn 1.95 N 0.05 O 4 electrodes were electrochemically characterized by using charge/discharge experiments along with ac impedance spectroscopy. The LiMn 1.95 Ni 0.05 O 4 electrode exhibited improved cycling performance in comparison with the stoichiometric LiMn 2 O 4 one in spite of a small reduction in the initial capacity. The good capacity retention of the LiMn 1.95 Ni 0.05 O 4 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.