Enhanced electrochemical performance of a cost-effective Sm2O3-coated spinel LiNi0.5Mn1.5O4 cathode for high-voltage lithium-ion batteries

Abstract

Spinel LiNi_0.5Mn_1.5O₄ (LNMO) has gained significant attention as a promising cathode material for lithium-ion batteries due to its high working voltage (>4.7 V) and energy density. However, challenges such as electrolyte decomposition-induced material interface erosion and transition metal dissolution under high operating voltage hinder its commercial use. In this study, a thin and uniform Sm₂O₃ layer has been successfully deposited on the surface of LNMO using a wet chemical method. A comprehensive investigation of surface morphology, crystal structure, and electrochemical performance of the modified LNMO is conducted. The results demonstrate that the Sm₂O₃ surface modification acts as a robust multifunctional protective layer, effectively shielding against hydrofluoric acid-induced chemical attack and enhancing the migration efficiency of lithium ions. Notably, the capacity retention rate of LNMO@Sm₂O₃ (3 wt%) remains up to 88 % after 280 cycles, significantly surpassing the uncoated counterpart. The coated material exhibits a capacity of 114 mAh g⁻¹ even under 10 C rate conditions. Moreover, the AC impedance values and manganese dissolution of the modified material in the organic electrolyte are considerably lower than those of the uncoated counterpart. Theoretical calculations strongly support the experimental findings, revealing higher Mn vacancy formation energy and density of states at the Fermi energy level for the Sm₂O₃-modified electrodes. This research contributes to the field of surface modification and paves the way for further enhancements in the electrochemical performance of other high-voltage manganese-based lithium-ion batteries (LIBs).