Impact of H2O exposure on the structure and electrochemical performance of LiVPO4F cathode material.

In this work, triclinic structured LiVPO 4 F is prepared by a simple two-step carbothermal reduction method and subsequently exposed to water under different storage conditions. The impact of exposure on the structure, morphology and electrochemical performance of LiVPO 4 F is investigated in detail. It is found that the effect of exposure at room temperature (20 °C) is slight. In contrast, exposure at 80 °C has great effect on the structure and electrochemical properties of LiVPO 4 F. Li, P and V dissolution into aqueous solution at 80 °C results in the formation of a yellowish solution. Electrochemical tests show that LiVPO 4 F samples aged in water at 80 °C for 3 and 5 days show poorer electrochemical properties than the pristine sample. LiVPO 4 F aged in water at 80 °C for 15 days exhibits higher initial reversible capacity compared with the pristine sample. However, it deteriorates rapidly in the following cycles due to the moisture-sensitive surface, which induces the formation of thick Li 2 CO 3 /Li 3 PO 4 film on the surface and leads to a high charge transfer resistance and the degradation of electrochemical performance. [ABSTRACT FROM AUTHOR]