Electrochemical performance of ALF₃-coated LiV₃O₈ for aqueous rechargeable lithium ion batteries

In aqueous rechargeable lithium ion batteries, LiV₃O₈ exhibits obviously enhanced electrochemical performance after AlF₃ surface modification owing to improved surface stability to fragile aqueous electrolyte. The cycle life of LiV₃O₈ is significantly enhanced by the presence of an AlF₃ coating at an optimal content of 1 wt.%. The results of powder X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, and galvanostatic charge-discharge measurements confirm that the electrochemical improvement can be attributed mainly to the presence of AlF₃ on the surface of LiV₃O₈. Furthermore, the AlF₃ coating significantly reduces vanadium ion dissolution and surface failure by stabilizing the surface of the LiV₃O₈ in an aqueous electrolyte solution. The results suggest that the AlF₃ coating can prevent the formation of unfavorable side reaction components and facilitate lithium ion diffusion, leading to reduced surface resistance and improved surface stability compared to bare LiV₃O₈ and affording enhanced electrochemical performance in aqueous electrolyte solutions.