Aluminum-stabilized NASICON-structured Li3V2(PO4)3

Abstract

The redox couple, V⁴⁺/V³⁺, exhibits a potential of 3.76 V in NASICON-structured Li₃Al_0.1V_1.9(PO₄)₃, which is suitable for a cathode material of a lithium-ion battery. The rhombohedral NASICON framework provides a large interstitial space for fast lithium transport, but the structure has to be prepared by the lithium ion-exchange method from NASICON-structured Na₃V₂(PO₄)₃. We used a LiNO₃ aqueous solution to treat Na₃V₂(PO₄)₃ for two weeks; a mixture of rhombohedral and monoclinic Li₃V₂(PO₄)₃ was obtained in the final product. Therefore, we introduced aluminum into the NASICON framework. Results from phase analysis and electrochemical evaluation have concluded that the aluminum stabilizes the NASICON framework of V₂(PO₄)₃ in the lithium ion-exchange process. The aluminum-stabilized Li₃Al_0.1V_1.9(PO₄)₃ showed a reversible capacity of 70 mA h g⁻¹ compared to 15 mA h g⁻¹ for the non-aluminum-doped n-LVP at 5C rate.