From the phase fraction analysis, it is clear that the Na2V2(PO4)3 phase could not be observed as completely isolated but rather coexisting together with the Na1V2(PO4)3 and Na3V2(PO4)3 ones. The maximum phase fraction of the Na2V2(PO4)3 phase observed during charge was of 30.1(8) wt% while it reached 77(1) wt% during discharge. The asymmetric behaviors in the appearance of the intermediate phase during charge and discharge were also observed in other studies of Na3V2(PO4)3 and of LiFePO4 . The intermediate phases of NaxV2(PO4)3 and LixFePO4 are more visible during charge in some cases and during discharge in other cases