Improving electrochemical performance of lithium-rich cathode material Li1.2Mn0.52Ni0.13Co0.13W0.02O2 coated with Li2WO4 for lithium ion batteries

Abstract

Lithium-rich manganese-based cathode materials face severe challenges, like initial irreversible capacity loss, poor cycling performance and rate capability, which seriously restrict their application in broader fields. In this work, Li2WO4-coated Li [Li0.2Mn0.52Ni0.13Co0.13W0.02]O2 has been successfully prepared by the sol-gel method with a calcination process. The measurements, such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy, are used to demonstrate Li2WO4 dispersion on the material surface. After coating with appropriate contents of Li2WO4, the materials display superior cycling performance and rate capability as well as low voltage decay. The optimal amounts of coating correspond to high capacity retentions of 87.5% at 1C and 88.7% at 5C, while the values only reach 72.9% and 75.9% for the pristine sample, respectively. In particular, when the coating content reaches 3 wt%, the rate capability is remarkably improved. The Li2WO4 coating layer can alleviate the corrosion of active materials and side reactions with electrolyte to enhance the cathode structural stability.