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

Abstract

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.