Improved electrochemical cycling performance of high-voltage spinel LiNi0.5Mn1.5O4 cathode materials by coating with spinel MgAl2O4

Abstract High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode materials suffer from degradation of the electrochemical cycling performance, particularly at elevated temperatures, which hinder their successful commercialization. In this work, we report that coating of this cathode material with the spinel MgAl2O4, which is similar in structure to LNMO, results in a significantly improved electrochemical cycling performance. The spinel MgAl2O4-coated LNMO was prepared by mixing LNMO powders in a solution of Mg(CH3COO)2·4H2O and Al(CH3COO)3·3H2O. The coated LNMO half-cell shows a capacity retention of 91.5% after 100 cycles at 25 °C, compared to 89.3% of the bare LNMO half-cell. At 55 °C, the effect of the coating is more significant, which is reflected by a capacity retention of 90.2% for the MgAl2O4-coated LNMO half-cell after 100 cycles at 55 °C. In contrast, the bare LNMO half-cell shows a smaller capacity retention of 66.9% after 100 cycles at 55 °C. The improved electrochemical cycling performance is attributed to the stabilized structure of LNMO and reduced electrolyte decomposition by the surface MgAl2O4 coating.