NaxVO2 as possible electrode for Na-ion batteries

We report the electrochemical properties vs. Na of the layered NaxVO2 phases having either octahedral or trigonal prismatic symmetries. Both phases can reversibly insert 0.5 Na atom per unit formula leading to sustained reversible capacities of nearly 120 mAh/g. Their voltage profile shows numerous voltage steps being mainly associated to subtle ordering of the Na ions within the layers while each phase preserves its initial structure through the entire Na insertion–deinsertion process.

► NaxVO2 lamellar phases as active material for Na-ion batteries negative electrode. ► Exchange of 0.5 Na leading to sustained reversible capacities of nearly 120 mAh/g. ► XRD studies confirm conservation of the average pristine structure.