Kashima-kita, Electric Power Corporation

Director General Agency of Industrial Science and Technology

Kanji Sato

Masato Nakajima

Toshiyuki Tayama

Yoshiteru Kageyama

Mitsutaka Miyabayashi

Hiroko Kaneko

Akira Negishi

Ken Nozaki

Toshiaki Akahoshi

Masatoshi Sawahata

Haruo Oyama

Ko Magome

Kouichi Furusato

Yutaka Nomura

Sumie Sekiguchi

The present invention relates to a liquid-circulating type redox flow battery which comprises

Redox flow type battery

The present invention provides a liquid-circulating battery including a positive electrode, a negative electrode, a permeable membrane interposed between the positive and negative electrodes to hold the same in separated relation to each other and to partition the same into a positive chamber and a negative chamber, two porous liquid-permeable carbon electrodes disposed respectively in the positive and negative electrolytic solutions being circulated respectively into the positive and negative chambers such that an oxidation-reduction reaction occurs and causes charging and discharging, wherein the permeable membrane is an ion-exchange me membrane including as an ion exchanger layer a polymeric pellicle which results from crosslinking of a halogenated alkylated product of an aromatic polysulfone type polymer with use of a polyamine and which has an ion exchange capacity of 0.3 to 8.0 milliequivalent/gram of dry resin and a thickness 0.1 to 120 .mu.m, said polysulfone type polymer having as a recurring unit a group represented at least by the following formula (I); and ##STR1## and wherein each of said positive and negative electrolytic solutions is an electrolytic solution having a vanadium ion concentration of 0.5 to 8 mols/liter.

Liquid-circulating battery

The present invention provides a redox battery using two layer, liquid permeable, porous electrodes, each having a porous electrode layer having high surface area comprising carbon fiber at the septum side and a porous electrode layer having low surface area comprising carbon fiber at the bipolar plate side. The battery has excellent properties such as high current density, low pump pressure loss, and high output.

Redox battery

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.sup.4+ and V.sup.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.

Method for producing high purity vanadium electrolytic solution

Tri- and tetravalent vanadium solutions suitable for a redox battery are produced as follows. Vanadium pentaoxide or ammonium vanadium is reduced in the presence of a concentrated sulfuric acid and a reducer, thus producing a solution containing tetravalent vanadium. At least a portion of the trivalent vanadium solution is heated to 180.degree.-250.degree. C., thus producing a trivalent vanadium compound. If the trivalent compound produced is a solid, it is collected and solubilized in water and/or sulfuric acid. Then, unreacted sulfur is filtered out, thus obtaining a trivalent vanadium solution.

Method for producing vanadium electrolytic solution

In a redox battery including an electrolytic cell which has a circulating type electrolytic solution and an intermittent circulating type electrolytic solution which has a membrane and which employs an electrolytic solution permeable porous electrode, a solution of vanadium (II/III) dissolved in sulfuric acid is used as an active material on the negative electrode of a redox couple, and an oxidizing substance in a gas (such as oxygen) or in electrolytic solution is used as an active material on the positive electrode of the redox couple. The redox battery of the invention shows high energy density, and has a small size and a high output, thus it can be used for an electric vehicle or as a portable battery.

Growing community of inventors

Kashima, Japan

Kanji Sato