Na₃V₂O_2x(PO₄)₂F_3−2x: a stable and high-voltage cathode material for aqueous sodium-ion batteries with high energy density

Abstract

The reversible electrochemical activity of the Na3V2O2x(PO4)2F3−2x compound in an aqueous solution is reported for the first time.

High‐Energy/Power and Low‐Temperature Cathode for Sodium‐Ion Batteries: In Situ XRD Study and Superior Full‐Cell Performance

“…The result is consistent with the No. 1535056 (tetragonal Na 3 V 2 (PO 4 ) 2 O 2 F) data in the Inorganic Crystal Structure Database, which suggests that the prepared material is mainly Na 3 V 2 (PO 4 ) 2 O 2 F, except for a small portion of Na 3 V 2 (PO 4 ) 2 F 3 phase with three extremely weak peaks at 2θ of 13.2°, 23.9°, and 31.3° in the PXRD pattern . The inset of Figure a gives the crystal structure of Na 3 V 2 (PO 4 ) 2 O 2 F, with a framework that is composed of VO 5 F octahedrons and PO 4 tetrahedrons.…”

Electrochemical studies of a high voltage Na4Co3(PO4)2P2O7–MWCNT composite through a selected stable electrolyte

“…4,5 To overcome these challenges, research on high-voltage and high-capacity cathode materials for SIBs is being conducted. 6 Different types of cathode materials have been studied, including the layered oxides such as Na 0.44 MnO 2 , 7 NaCoO 2 , 8 O3-NaNi 0.5 -Mn 0.5 O 2 , 9 and P2-Na 2/3 Fe 1/2 Mn 1/2 O 2 ; 10 phosphates such as NaFePO 4 , 11 Na 1.8 Fe 3 (PO 4 ) 3 , Na 2 M 2 Fe(PO 4 ) 3 (where M ¼ Ni and Co), Na 4 MnV(PO 4 ) 3 , Na 3 V 2 (PO 4 ) 3 , 12 NaTi 2 (PO 4 ) 3 , 13 Na 3 V 2 (PO 4 ) 3 -F 3 , 14 Na 3 V 2 O 2 (PO 4 ) 3 F, 15 and Na 2 FeP 2 O 7 ; 16 sulfates such as NaFe(SO 4 ) 2 (ref. 17) and NaFe 2 (PO 4 )(SO 4 ) 2 ; 18 and the Prussian blue derivatives Na 2 NiFe(CN) 6 (ref.…”

Na2FePO4F Fluorophosphate as Positive Insertion Material for Aqueous Sodium‐Ion Batteries

“…Following the first report on aqueous sodium-ion energy storage device using Na 0.44 MnO 2 (Na 4 Mn 9 O 18 ) by Whitacre et al, several other cathode materials such as Na 0.24 MnO 2 , λ-MnO 2 , NaVPO 4 F, Na 3 V 2 O 2x (PO 4 ) 2 F 3-2x , Na 2 NiFe(CN) 6 and Na 2 MnFe(CN) 6 have been explored. [17][18][19][20][21][22][23][24] Owing to large amounts of defects in the structure, these materials have poor capacity retention in aqueous batteries. On another note, NaTi 2 (PO 4 ) 3 was reported as an efficient anode for aqueous SIBs having a NASICON type framework generating large interstitial spaces for Na + diffusion.…”