A novel lithium vanadium fluorophosphate nanosheet with uniform carbon coating as a cathode material for lithium-ion batteries

摘要

Lithium vanadium fluorophosphate (LiVPO_4F/C) nanosheets with uniform carbon coating are successfully synthesized using a hydrothermal method followed by calcination. X-ray diffraction results reveal that the obtained products crystallized in the triclinic LiVPO_4F phase. Scanning electron microscope and transmission electron microscope images demonstrate that both vanadium phosphate (VPO_4/C) and LiVPO_4F/C composites have a very flat sheet-like morphology, with each nanosheet exhibiting a smooth surface and a typical thickness of 50-100 nm. The nanosheets are coated by a uniform layer of amorphous carbon. Electrochemical tests show that LiVPO_4F nanosheets deliver a discharge capacity of 143 mAh g~(-1) at 0.1 C in the range of 3.0-4.5 V at the first cycle and possess a favorable capacity at rates of 0.5,1, 2, 3 and 5 C.