Coherent deposits of oriented, crystalline MxM′4−xV6O16+δ, with M, M′ = K, Rb, Cs, or NH4, 0.0 ≤ x ≤4.0 and 0.00 ≤ δ ≤ 0.13, have been prepared electrochemically on various conducting substrates from metavanadate solutions containing ammonium or alkali metal cations, singly or in combination. Chemical analysis and X-ray diffraction show that the deposits consist of a continuous series of mixed crystals based on the isomorphic end members M4V6O16 and M′4V6O16.The deposits can be oxidized electrochemically, with removal of M and M′ atoms, and the products can be used as cathodes for insertion of lithium, with the largest capacity achieved about 1.0 mol% of total vanadium. Cycling of the electrodes improves capacity, with insertion of lithium reaching 25 mol% of total vanadium. This gain in capacity results from further removal of alkali metal or ammonium ions from the electrode during the oxidation step of the cycling process.The results extend the range of composition of homogeneous phases in the system (NH4)2O–K2O–V2O4–V2O5. Keywords: alkali metal hexavanadates, electrochemical preparation.On a préparé des dépôts cohérents qui contiennent des cristaux orientés de MxM′4−xV6O16+δ, avec M, M′ = K, Rb, Cs ou NH4, 0,0 ≤ x ≤4,0 et 0,00 ≤ δ ≤ 0,13, par la méthode de voltammétrie cyclique sur des substrats divers et dans des solutions de metavanadates qui contiennent des cations des métaux alcalins ou d'ammonium seuls ou des combinations de tels ions. L'analyse chimique et la diffraction des rayons X ont démontré que les dépôts comprennent une série continue de cristaux mixtes basée sur les membres terminaux M4V6O16 et M′4V6O16.
Chemical analysis of alkali metal tungsten bronzes