Multiphase LiNi_0.33Mn_0.54Co_0.13O₂ Cathode Material with High Capacity Retention for Li-Ion Batteries

An integrated layered-spinel LiNi_0.33Mn_0.54Co_0.13O₂ material was synthesized through a self-combustion reaction (SCR), characterized by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and Raman spectroscopy. It was studied as a cathode material for Li-ion batteries and its electrochemical performance was compared with that of the layered cathode material LiNi_0.33Mn_0.33Co_0.33O₂ when operated over a wide potential window. The Rietveld analysis of LiNi_0.33Mn_0.54Co_0.13O₂ indicated the presence of monoclinic Li[Li_1/3Mn_2/3]O₂ (31%) and rhombohedral (LiNi_xMn_yCo_zO₂) (62%) phases as the major components, and the spinel (LiNi_0.5Mn_1.5O₄) (7%) as a minor component, which is supported by TEM and electron diffraction analyses. A discharge specific capacity of about 170mAhg^-1 is obtained in the potential range of 2.3-4.9V versus Li at low rate (C/10) with excellent capacity retention upon cycling. On the other hand, LiNi_0.33Mn_0.33Co_0.33O₂ (NMC111) synthesized through SCR exhibits an initial discharge capacity of about 208mAhg^-1 in the potential range of 2.3-4.9V, which decreases to a value of 130mAhg^-1 after only 50 cycles. In turn, the multiphase structure of LiNi_0.33Mn_0.54Co_0.13O₂ seems to stabilize the behavior of this cathode material, even when polarized to high potentials. LiNi_0.33Mn_0.54Co_0.13O₂ shows superior retention of the average discharge voltage upon cycling, as compared to that of LiNi_0.33Mn_0.33Co_0.33O₂ when cycled over a wide potential range. Overall, LiNi_0.33Mn_0.54Co_0.13O₂ can be considered as a promising low-cobalt-content cathode material for Li-ion batteries.