Preparation and characterization of yttrium-doped high voltage spinel LiNi0.5Mn1.5O4 for lithium-ion batteries

Abstract

LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for Li-ion batteries due to its high potential plateau of 4.7V and environmentally friendly. However, LNMO experiences rapid performance degradation when the operation voltage is over 4.2V. One of the effective ways to improve cycling stability is doping. In this study, the LNMO cathode was doped with Yttrium (LiNi0.5Mn1.5-xYxO4, x=0, 0.01, 0.03, 0.05). Mn2O3 microsphere precursor was synthesized by calcining MnCO3 prepared by precipitation of MnSO4 using (NH4)2CO3 as precipitant. A stoichiometric amount of Ni(CH3COO)2, Li2CO3, and Y(NO3)3 were dissolved in minimum water. The mixed solution was then poured thoroughly into acetone dispersed with a proper amount of Mn2O3. The suspension formed was evaporated slowly under continuous stirring to obtain a uniform mixture. The calcination process was conducted at 800°C for 6 hours. SEM image showed that the micro-spherical morphology of LiNi0.5Mn1.5-xYxO4 samples was maintained from the Mn2O3 precursor. Obtained XRD patterns of samples were identified as disordered spinel LNMO with a space group of Fd-3m. LiNi0.5Mn1.45Y0.05O4 sample showed the highest discharge capacity at 0.1C among pristine and other Y-doped LNMO samples.