Enhanced Electrochemical Capability of LiNi1/3Co1/3Mn1/3O2 Cathode Materials Coated with Fluoroborate Glass for Lithium‐Ion Batteries

Abstract

AbstractA LiNi1/3Co1/3Mn1/3O2 (NCM) cathode material is coated with fluoroborate glass (xLi2O‐yB2O3‐zLiF) to improve the electrochemical performance of lithium‐ion batteries. An xLi2O‐yB2O3‐zLiF layer was successfully coated onto the surface of NCM by using a solution‐phase method. The resulting materials are characterized by using X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The xLi2O‐yB2O3‐zLiF‐coated NCM exhibits a superior discharge capacity, rate capability, and cycling stability than those of the uncoated material. Notably, the initial discharge capacity of bare and 2Li2O‐B2O3‐LiF‐coated NCM were 182.1 and 207.5 mAhg−1, respectively, in the voltage range from 2.5 to 4.5 V. At a rate of 5C, the discharge capacity of Li2O‐B2O3‐LiF‐coated NCM is 144.4 mAhg−1, whereas that of bare NCM is 76.7 mAhg−1. After 50 cycles at a rate of 0.2C, the capacity retentions of Li2O‐B2O3‐LiF‐, 2Li2O‐B2O3‐LiF‐, Li2O‐2B2O3‐LiF‐, and Li2O‐B2O3‐2LiF‐coated NCM are 96.8, 97.2, 95.6, and 95.2%, respectively, whereas the capacity retention of bare NCM is 81.4%. Cyclic voltammetry and electrochemical impedance spectroscopy results indicate that the xLi2O‐yB2O3‐zLiF coating reduces electrode polarization and decreases charge‐transfer resistance at the electrolyte–electrode interface, further improving the electrochemical activity of the NCM cathode material.