Excellent cycling stability of spherical spinel LiMn2O4 by Y2O3 coating for lithium-ion batteries

Abstract

The Y2O3 nano-film is coated on the surface of the spherical spinel LiMn2O4 by precipitation method and subsequent heat treatment at 550 °C for 5 h in air. The structure and performance of the bare LiMn2O4 and Y2O3-coated LiMn2O4 are characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive analysis X-ray spectroscopy, galvanostatic charge–discharge, cyclic voltammetry, and impedance spectroscopy. It has been found that the addition of Y2O3 does not change the bulk structure of LiMn2O4, and the thickness of the Y2O3 coating layer is approximate to 3.0 nm. The 1 wt% Y2O3-coated LiMn2O4 electrode reveals excellent cycling performance with 80.3 % capacity retention after 500 cycles at 1 C at 25 °C. When cycling at elevated temperature 55 °C, the as-prepared sample still shows 76.7 % capacity retention after 500 cycles. These remarkable improvements indicate that thin Y2O3 coating on the surface of LiMn2O4 is an effective way to improve the electrochemistry performance. Besides, the suppression of Mn dissolution into the electrolyte via the Y2O3 coating layer can be accounted for the improved performances.