The present invention relates to a membrane electrode unit comprising a polymer membrane doped with a mineral acid as well as two electrodes, characterized in that the polymer membrane comprises at least one polymer with at least one nitrogen atom and at least one electrode comprises a catalyst which is formed from at least one precious metal and at least one metal less precious according to the electrochemical series.

The present invention relates to a membrane electrode unit comprising a polymer membrane doped with a mineral acid as well as two electrodes, characterized in that the polymer membrane comprises at least one polymer with at least one nitrogen atom and at least one electrode comprises a catalyst which is formed from at least one precious metal and at least one metal less precious according to the electrochemical series.

An electrolyte membrane of a membrane-electrode assembly is formed by a manufacturing method yielding a membrane with improved chemical durability. The manufacturing method includes preparing an antioxidant solution, mixing the antioxidant solution and a first ionomer dispersion solution, drying the mixture to produce a composite having an antioxidant and a first ionomer surrounding the antioxidant, introducing and mixing the composite with a second ionomer dispersion solution, and applying that mixture to a substrate and drying the mixture to manufacture an electrolyte membrane. The resulting electrolyte membrane includes the composite having an antioxidant in an ionic state and a first ionomer surrounding the antioxidant.

An electrolyte membrane of a membrane-electrode assembly is formed by a manufacturing method yielding a membrane with improved chemical durability. The manufacturing method includes preparing an antioxidant solution, mixing the antioxidant solution and a first ionomer dispersion solution, drying the mixture to produce a composite having an antioxidant and a first ionomer surrounding the antioxidant, introducing and mixing the composite with a second ionomer dispersion solution, and applying that mixture to a substrate and drying the mixture to manufacture an electrolyte membrane. The resulting electrolyte membrane includes the composite having an antioxidant in an ionic state and a first ionomer surrounding the antioxidant.

Disclosed are redox flow battery membranes, redox flow batteries incorporating the membranes, and methods of forming the membranes. The membranes include a densified polybenzimidazole gel membrane that is capable of incorporating a high liquid content without loss of structure that is formed according to a process that includes in situ hydrolysis of a polyphosphoric acid solvent followed by densification of the gel membrane. The densified membranes are then imbibed with a redox flow battery supporting electrolyte such as sulfuric acid and can operate at very high ionic conductivities of about 50 mS/cm or greater and with low permeability of redox couple ions, e.g. vanadium ions, of about 10.sup.−7 cm.sup.2/s or less. Redox flow batteries incorporating the membranes can operate at current densities of about 50 mA/cm.sup.2 or greater.

Disclosed are redox flow battery membranes, redox flow batteries incorporating the membranes, and methods of forming the membranes. The membranes include a densified polybenzimidazole gel membrane that is capable of incorporating a high liquid content without loss of structure that is formed according to a process that includes in situ hydrolysis of a polyphosphoric acid solvent followed by densification of the gel membrane. The densified membranes are then imbibed with a redox flow battery supporting electrolyte such as sulfuric acid and can operate at very high ionic conductivities of about 50 mS/cm or greater and with low permeability of redox couple ions, e.g. vanadium ions, of about 10.sup.−7 cm.sup.2/s or less. Redox flow batteries incorporating the membranes can operate at current densities of about 50 mA/cm.sup.2 or greater.

Disclosed are a membrane-electrode assembly and a method for manufacturing the same. The membrane-electrode assembly has durability and proton conductivity which are improved by employing an ion conductive polymer having improved chemical durability and ion conductivity.

Disclosed are a membrane-electrode assembly and a method for manufacturing the same. The membrane-electrode assembly has durability and proton conductivity which are improved by employing an ion conductive polymer having improved chemical durability and ion conductivity.

A zinc iodine flow battery includes a positive end plate, a positive current collector, a negative current collector, a positive electrode with a flow frame, a membrane, a negative electrode with a flow frame, a negative end plate. The negative electrolyte is circulated between the negative storage tank and the negative cavity by pump. The negative pipe is provided with a branch pipe for the positive electrolyte circulation. The porous membrane between the positive and negative electrodes can realize the conduction of supporting electrolyte and prevent the diffusion of I3− to the negative electrolyte. In a duel-flow battery system, same electrolyte serves as both the positive electrolyte and the negative electrolyte, which is a mixed aqueous solution containing iodized and zinc salt. The membrane is porous membrane does not contain ion exchange group. Both the positive and negative electrolyte are neutral solutions.

A proton-conducting polymer comprises a plurality of repeating units of formula (I) for electrochemical reactions. The polymer may be synthesized from a super acid catalyzed polyhydroxyalkylation reaction of monomers Ar.sub.1′, Ar.sub.2′, and X.sub.1′ followed by a nucleophilic substitution reaction or a grafting reaction, and optionally an acidification reaction.

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Proton-exchange membranes and membrane electrode assemblies made from the polymer are also described.