A₂VO(SO₄)₂ (A = Li, Na) as Electrodes for Li-Ion and Na-Ion Batteries

We herein report the synthesis, crystal structure, and electrochemical performances of a new Li-based vanadium oxysulfate phase, Li2VO(SO4)2, whose structure is built on vanadyl-containing VO5 square-based pyramids and SO4 groups linked by vertices to form layers. Li2VO(SO4)2 presents a redox activity at 4.7 V vs Li+/Li0 with a reversible capacity of 50 mA·h/g, while the chemically similar but structurally different Na2VO(SO4)2 delivers a capacity of 60 mA h/g at 4.5 V vs Na+/Na0. Density functional theory calculations are also performed to rationalize our findings in terms of redox activity and phase stability.