Improved electrochemical behavior of Li rich cathode Li1.4Mn0.61Ni0.18Co0.18Al0.03O2.4 via Y2O3 surface coating

Abstract

Better electrochemical properties of lithium batteries are achieved by a two-step solid state method with Y2O3 protective layer coated on Li1.4Mn0.61Ni0.18Co0.18Al0.03O2.4 (LNCMA) layered cathode material to meet the new requirements. XRD, TEM and various electrochemical investigations are used to reveal the fine structure and electrochemical behavior of the prepared Y2O3/LNCMA materials. The result indicates that Y2O3 layer covers the surface of the LNCMA cathode in our approach. Although Y2O3 coated LNCMA displays slight decrease in the initial capacity when compared with the original Li rich phase, the cathode with 3 wt% Y2O3 coating shows promoted cyclability with 92.9% capacity retention after 100 cycles at 0.2C and an improved rate behavior of 124.1 mAh g−1 even at 10C. Such an obvious increase in electrochemical behavior can be explained by the reduced interfacial resistance and increased ionic diffusion which caused by the suppressed transition metal dissolution in the electrolyte, as confirmed from the impedance spectra. The above results greatly suggest that Y2O3/LNCMA material can be applied as a potential cathode in LIBs with high energy.