Preparation and characteristics of δ-Na_yAg_0.70-yV₂O₅ as a lithium insertion host

The oxide bronzes, δ-Na_yAg_0.70-yV₂O₅, were prepared both by solid state and ion-exchange reactions, and their lithium insertion/extraction behaviors were examined. Single phase oxide bronzes were obtained at 0≤y≤0.2 by the solid state reaction and at 0≤y≤0.5 by the ion-exchange reaction. Reduction of silver(I) in the lithium insertion reaction occurred in succession to the reduction of vanadium(V) to vanadium(IV) up to V^IV/V^V = 1. Reversible insertion/extraction of lithium without changing the layer structure occurred when the total amount of interlayer cations was two in the formula unit, almost independent of the content of sodium ions in the interlayer.