Synthesis and cycling performance of double metal doped LiMn2O4 cathode materials for rechargeable lithium ion batteries

In order to improve the cycling performance of LiMn₂O₄, the spinel phases LiCo_0.15Mn_1.85O₄ and LiCo_0.05M_0.1Mn_1.85O₄ (M = Ni, Zn, Cu) were prepared by the sol-gel method. Their structures have been investigated by x-ray diffraction. Electrochemical studies were carried out using the Li | Li _x Mn₂O₄ (x = 1.05, 1.1), LiCo_0.15Mn_1.85O₄, and LiCo_0.05M_0.1Mn_1.85O₄ (M = Ni, Zn, Cu) cells. The capacity loss of Li | Li _x Mn₂O₄ (x = 1.05, 1.1) cells is about 21.7 and 6.4% after 30 cycles, whereas that for Co, Co-Ni, Co-Zn, and Co-Cu doped spinel materials is about 4.0, 2.0, 1.0, and 1.9%, respectively. The good capacity retention of LiCo_0.05M_0.1Mn_1.85O₄ (M = Ni, Zn, Cu) electrodes is attributed to stabilization of spinel structure by double metal doping for Mn ion sites. Double substituted spinels display better performance in terms of cycle-life compared with LiMn₂O₄. The text was submitted by the authors in English.