Synthesis, Characterization, and Comparison of Electrochemical Properties of LiM0.5Mn1.5O4 (M = Fe, Co, Ni) at Different Temperatures

LiM0.5Mn1.5O4 [M = Fe, Co, Ni] normal spinel oxides were prepared by a citric acid assisted Pechini synthesis with different thermal treatments and compared with respect to their electrochemical performance as cathodes in lithium-ion batteries. Characterization methods include X-ray diffraction, neutron diffraction, inductively coupled plasma optical emission spectroscopy analysis, and scanning electron microscopy. While LiM0.5Mn1.5O4 samples crystallize for M = Fe and Co with the 3d cation-disordered cubic spinel-like structure (Fd3m space group), the 600 degrees C annealed LiNi0.5Mn1.5O4 shows a partially ordered structure (belonging to the P4(3)32 space group). The absolute discharge capacity is slightly higher for the Ni-doped samples in comparison with the Co- and Fe-doped spinels. 1000 degrees C annealed samples show an improved cyclability in comparison with the 600 degrees C annealed samples. At elevated temperatures, Co- and Fe-doped samples show much faster degradation in comparison with the Ni-doped sample. The responsible mechanisms are discussed. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3365025] All rights reserved.