Na7V3(P2O7)(4) as a high voltage electrode material for Na-ion batteries: crystal structure and mechanism of Na+ extraction/insertion by operando X-ray diffraction

Vadim M. Kovrugin (1) , Jean-Noel Chotard (1, 2, 3) , Francois Fauth (4) , Christian Masquelier (1, 2)

1 LRCS - Laboratoire réactivité et chimie des solides - UMR CNRS 7314
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 ALISTORE-ERI - Advanced Lithium Energy Storage Systems - ALISTORE-ERI
4 CELLS ALBA, Barcelona 08290, Spain

The crystal chemistry and the electrochemical properties of Na7V3(P2O7)(4) as a high voltage cathode material upon Na+ extraction/insertion were investigated. The crystal structure was solved and refined for the first time from single crystal X-ray diffraction data. Possible sodium migration pathways were determined using the bond valence energy landscape (BVEL) method based on the bond valence theory. The electrochemical behavior of the material in a wide voltage range demonstrates the activity of the V3+/V4+, V4+/V5+, and V3+/V2+ redox couples. The reversible capacity of the Na7V3(P2O7)(4) electrode is hence increased up to 118 mA h g(-1)vs. Na+/Na. Sodium extraction/insertion mechanisms are examined by operando X-ray diffraction, which provides direct information on the evolution of the material in nonequilibrium states upon electrochemical oxidation and reduction processes.

Domaines: Chimie; Matériaux

Vadim M. Kovrugin, Jean-Noel Chotard, Francois Fauth, Christian Masquelier. Na7V3(P2O7)(4) as a high voltage electrode material for Na-ion batteries: crystal structure and mechanism of Na+ extraction/insertion by operando X-ray diffraction. Journal of Materials Chemistry A, 2020, 8 (40), pp.21110-21121. ⟨10.1039/d0ta06230h⟩. ⟨hal-03611088⟩