NASICON-type NaMo2(PO4)3: Electrochemical activity of the Mo+4 polyanion compound in Na-cell. (1st November 2018)

• Record Type: Journal Article
• Authors: Panin, Rodion V.; Drozhzhin, Oleg A.; Fedotov, Stanislav S.; Khasanova, Nellie R.; Antipov, Evgeny V.
• Is Part Of: Electrochimica acta. Volume 289(2018)
• Page Start: 168
• Page End: 174
• Publication Date: 2018-11-01
• Subjects: Na-ion battery -- NASICON-type materials -- Freeze drying -- Multi-electron redox transitions -- Reversible sodium (de)intercalation; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.09.045
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Vital need to reduce battery cost inspired intensive research in the field of sodium-storage systems, which required extending the range of perspective electrode materials. Herein, we present a new member of the electrochemically active NASICON material family, rhombohedral NaMo2 (PO4 )3, which demonstrates both Mo +4 /Mo +5 and Mo +4 /Mo +3 redox activities towards sodium (de)intercalation. Desodiation of the initial NaMo2 (PO4 )3 material with subsequent discharge within the 1.2–4.0 V range leads to a multi-electron redox transition with reversible capacity of 130 mAh g −1 . However, the single Mo +4 /Mo +3 redox transition at 2.45 V ( vs . Na/Na + ) with capacity of 95 mAh g −1 was found to be more stable during cycling, and operando X-ray diffraction confirmed its two-phase mechanism. Sodiation of the initial phase results in Na2.5 Mo2 (PO4 )3, which maintains the parent NASICON structure ( R -3c, a = 8.90532(7) Å, c = 22.2379(3) Å, V = 1527.30(3) Å 3 ), with two Na-positions being almost equal in occupancy and energy. Graphical abstract: Highlights: NASICON-type NaMo2 (PO4 )3 electrode material was prepared by freeze-drying technique. NaMo2 (PO4 )3 shows partially reversible Na-deintercalation above 3.6 V vs. Na/Na + . Reversible insertion of 1.8 Na occurs at 2.45 V vs. Na/Na + via two-phase mechanism. Na-rich Na1+x Mo2 (PO4 )3 phase maintains the NASICON-type framework.