Improved electrochemical performance of the spherical LiNi0.5Mn1.5O4 particles modified by nano-Y2O3 coating

Abstract

The large-scale use of LiNi0.5Mn1.5O4 as the cathode material for lithium-ion battery has so far been hindered by some drawbacks, for example, the interfacial side reactions between the high-voltage charged LiNi0.5Mn1.5O4 and the liquid electrolyte. Herein, the spherical LiNi0.5Mn1.5O4 is synthesized via co-precipitation method, and then the as-prepared LiNi0.5Mn1.5O4 is modified by nano-Y2O3 coating through heterogeneous nucleation route in order to improve its electrochemical performance. The effects of nano-Y2O3 coating on structural and electrochemical performance of LiNi0.5Mn1.5O4 are systematically investigated by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic absorption spectroscopy, and electrochemical measurements. The results demonstrate that the surface of LiNi0.5Mn1.5O4 particle is uniformly encapsulated by nano-Y2O3 coating. Meanwhile, although the nano-Y2O3 coating can still keep the spinel structure of LiNi0.5Mn1.5O4, it can apparently improve its electrochemical performance. The nano-Y2O3-coated LiNi0.5Mn1.5O4 sample can deliver an initial discharge capacity of 126.1 mAh g−1 with the capacity retention of 97.7 % after 300 cycles at current rate of 1 C at 25 °C. Particularly, the nano-Y2O3-coated LiNi0.5Mn1.5O4 sample exhibits excellent capacity retention of 91.6 % after 100 cycles even at elevated temperature and a rate of 2 C.