Method for producing high purity vanadium electrolytic solution

摘要

A method for producing an electrolytic solution containing vanadium as positive and negative electrode active material, the electrolytic solutions being suitable for a redox battery which comprises: the steps of (1) a vanadium compound is dissolved in a solvent under an alkaline or neutral condition, a polyvanadate compound is precipitated and isolated by thermal polymerization of vanadium ions under an acidic condition; (2) a part of the polyvanadate compound is baked in an inert or oxidizing gas atmosphere so as to remove ammonium ions; (3) a trivalent vanadium compound is formed by treating another part of the polyvanadate compound under a reductive atmosphere; (4) a trivalent vanadium electrolytic solution is formed by dissolving the trivalent vanadium compound in an acid solution; and (5) vanadium pentoxide and a part of the trivalent vanadium compound are reacted by mixing so that mixed electrolytic solutions of V<4><+> and V<3><+> are formed. According to the present invention, a high purity vanadium electrolytic solution can be economically produced even from vanadium pentoxide and ammonium metavanadate raw materials containing large quantities of impurities.