Effects of Al2O3 and AlF3 coating on the electrochemical performance of Li3V2(PO4)3/C cathode material in lithium ion batteries

• AlF3 and Al2O3 have been coated on the surface of Li3V2(PO4)3/C.
• AlF3 and Al2O3 coating can suppress the electrolyte decomposition and vanadium dissolution in a high voltage region.
• Cycling performance is improved after coating the surface.
• LiF peak at F 1s spectra has been reduced and C–C peak at C 1s spectra has maintained its peak after AlF3 and Al2O3 coating.

Surface modified Li3V2(PO4)3/C materials have been prepared by coating with AlF3 and Al2O3 via a conventional precipitation method. X-ray diffraction patterns indicate that the surface modification does not affect to the bulk structure of Li3V2(PO4)3. Field emission scanning electron microscopy and field emission transmission electron microscopy show that an amorphous carbon layer and particles of AlF3 and Al2O3 are coated on the surface of Li3V2(PO4)3 particles. Both AlF3- and Al2O3-coated materials exhibit better cycling performance than the uncoated Li3V2(PO4)3/C between 3.0 and 4.8 V. The capacity retention rates of LVP/C, LVP/C-AlF3, and LVP/C-Al2O3 after 50 cycles at 0.2 C are 76.12, 85.39, and 84.99%, respectively.