The effects of AlF3 modification of the surface of Li2FeP2O7/C cathode material for high electrochemical performance

Abstract

The surface of Li2FeP2O7/C modified by AlF3 was prepared by solid-state synthesis and a sol-gel coating process. The monoclinic crystal structure with a P 21/c space group was characterized by XRD for as-prepared and different ratios of AlF3-coated Li2FeP2O7/C. The chemical bonds for Al and F were examined by XPS spectra. The morphologies were observed by FE-SEM and HR-TEM. The electrochemical measurements, such as EIS, CV, and galvanostatic charge-discharge, were conducted, and 1.0 wt% AlF3-coated Li2F3P2O7/C revealed the lowest charge-transfer resistance and IR drop of all compared groups. The rate capability of the 1.0 wt% AlF3-coated Li2FeP2O7/C was improved over that of the uncoated Li2FeP2O7/C and of different coating-ratio samples. Finally, the surface modification of Li2FeP2O7/C coated with 1.0 wt% of AlF3 is an effective way to improve the electrochemical performance in the Li2FeP2O7/C cathode.