10361-03-2Relevant articles and documents
Crystal structures and local environments of NASICON-type Na3FeV(PO4)3and Na4FeV(PO4)3positive electrode materials for Na-Ion batteries
Carlier, Dany,Chotard, Jean-No?l,Courty, Matthieu,Croguennec, Laurence,Duttine, Mathieu,Fauth, Fran?ois,Iadecola, Antonella,Masquelier, Christian,Moog, Iona,Park, Sunkyu
, p. 5355 - 5367 (2021)
In this work, we investigate the crystal chemistry of Fe/V-mixed NASICON [sodium (Na) Super Ionic CONductor] compositions Na3FeV(PO4)3 and Na4FeV(PO4)3 that are structurally related to Na3V2(PO4)3, a positive electrode for Na-ion batteries. To synthesize Na4FeV(PO4)3, various synthesis routes (solid-state, sol-gel-assisted, and electrochemical syntheses) were investigated. Direct syntheses resulted in the formation of a NASICON-type phase in the presence of NaFePO4 and Na3PO4 impurities. The successful preparation of pure Na4FeV(PO4)3 has been achieved by the electrochemical sodiation of Na3FeV(PO4)3. Both synchrotron X-ray absorption and M?ssbauer spectroscopy allowed probing the local V and Fe environments and their oxidation states in Na3FeV(PO4)3 and Na4FeV(PO4)3. Na3FeV(PO4)3 crystallizes in the space group C2/c (a = 15.1394(2) ? b = 8.72550(12) ? c = 21.6142(3) ? β = 90.1744(9)° and Z = 12), and it is isostructural to an ordered α-form of Na3M2(PO4)3 (M = Fe, V). It presents a superstructure due to Na+ ordering, as confirmed by differential scanning calorimetry and in situ temperature X-ray diffraction. The electrochemically sodiated Na4FeV(PO4)3 powder crystallizes in the space group R3ˉ c (a = 8.94656(8) ?, c = 21.3054(3) ?, and Z = 6) within which the two sodium sites, Na(1) and Na(2), are almost fully occupied. Na4FeV(PO4)3 allows the electrochemical extraction of 2.76 Na+ per formula unit within the voltage range of 1.3-4.3 V versus Na+/Na through the FeIII/II, VIV/III, and VV/IV redox couples. This identifies an interesting material for Na-ion batteries.
Synthesis and structure of bis-hexaaquasodium bis-nitrilotris(methylenephosphonato)decaaquamonohydrohexasodiumlanthanate trihydrate [Na(H2O)6]2[LaNa6H(H2O)10{N(CH2PO3)3}2] · 3H2O
Somov,Chausov,Zakirova,Petrov,Shumilova,Aleksandrov
, p. 373 - 379 (2017)
A complex salt of nitrilotris(methylenephosphonic acid) with sodium and lanthanum was prepared, isolated, and studied. The salt [Na(H2O)6]2[LaNa6H(H2O)10{N(CH2PO3)3}2] · 3H2O crystallizes in space group P21/c, Z = 2, a = 11.86630(10), b = 10.55060(10), c = 19.99270(10) ?, β = 94.6760°. The La coordination polyhedron is a virtually regular rhombohedron. The Na atom is coordinated at the vertices of a distorted octahedron. Both ligand molecules chelate the La atom; each PO3 group forms a La–O–P–O–Na bridge; the ligand denticity is 7.