The Effects of AlF3 Coating on the Performance of Li [ Li0.2Mn0.54Ni0.13Co0.13 ] O2 Positive Electrode Material for Lithium-Ion Battery

Abstract

-coated materials have been synthesized as positive electrode materials for lithium-ion batteries. The pristine and -coated materials were characterized by X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and charge–discharge techniques. The electrochemical studies indicated that the -coated showed initial irreversible capacity loss of only compared to for pristine material. Meanwhile, the coated material also exhibited better rate capability and cyclic performance, which has higher capacity retention of 87.9% after at rate at room temperature in comparison with only 67.8% for the pristine one. The functional mechanism of coating on the performance of was also investigated by electrochemical impedance spectroscopy (EIS) and in situ differential electrochemical mass spectrometry (DEMS). EIS analysis indicated that -coated had stable charge transfer resistance . In situ DEMS results revealed that the activity of extracted oxygen species from layered positive electrode material was greatly reduced and the decomposition of the electrolyte was significantly suppressed for -coated . Therefore, more oxygen molecules rather than carbon dioxide were observed in the coated material system. It is demonstrated again that the coating layer played an important role in the stabilization of the electrode/electrolyte interface for the coated material.