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 LiCo0.15Mn1.85O4 and LiCo0.05M0.1Mn1.85O4 (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), LiCo0.15Mn1.85O4, and LiCo0.05M0.1Mn1.85O4 (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 LiCo0.05M0.1Mn1.85O4 (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.