Aluminum-stabilized NASICON-structured Li3V2(PO4)3
The redox couple, V4+/V3+, exhibits a potential of 3.76 V in NASICON-structured Li3Al0.1V1.9(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 Li3Al0.1V1.9(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.