The present invention relates to an ion exchange membrane and an energy storage device comprising same, wherein the ion exchange membrane comprises: a polymer membrane comprising an ion conductor; and any one ion permeation inhibiting additive selected from the group consisting of a columnar porous metal oxide, crown ether, a nitrogen-containing cyclic compound, and a mixture thereof. In the ion exchange membrane, the size of a channel through which ions permeate is limited or an additive capable of trapping ions is introduced into an ion movement path, so that the permeation of ions is prevented, leading to the improvement of voltage efficiency and the prevention of deterioration.

A polybenzimidazole production method for producing the polybenzimidazole including a repeating unit represented by the following formula (1):

##STR00001##

wherein R.sup.f is —SO.sub.2—, —O—, —CO—, an alkylene group optionally containing a substituent, or a group represented by the following formula (a):

##STR00002##

two Xs are each individually a hydrogen atom or a monovalent organic group; and R.sup.1 is a divalent organic group, the production method including a step (1-1) of polymerizing a tetramine compound and a dicarboxylic acid derivative compound to provide a polybenzimidazole precursor polyamide, and a step (1-2) of dehydrocyclizing the polybenzimidazole precursor polyamide.

A polybenzimidazole production method for producing the polybenzimidazole including a repeating unit represented by the following formula (1):

##STR00001##

wherein R.sup.f is —SO.sub.2—, —O—, —CO—, an alkylene group optionally containing a substituent, or a group represented by the following formula (a):

##STR00002##

two Xs are each individually a hydrogen atom or a monovalent organic group; and R.sup.1 is a divalent organic group, the production method including a step (1-1) of polymerizing a tetramine compound and a dicarboxylic acid derivative compound to provide a polybenzimidazole precursor polyamide, and a step (1-2) of dehydrocyclizing the polybenzimidazole precursor polyamide.

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.

##STR00001##

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

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.

##STR00001##

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

Provided is an electrolyte membrane including at least the following: an A-layer composed of an ion-conducting fluorinated polymer and a non-ion-conducting fluorinated polymer; and a B-layer composed of an ion-conducting hydrocarbon polymer, wherein the ion-conducting hydrocarbon polymer is dispersed in the A-layer. Provided is an electrolyte membrane having excellent oxidation resistance. In addition, provided is an electrolyte membrane for a redox-flow battery, in which the electrolyte membrane used as a barrier membrane for a redox-flow battery makes it possible to achieve high power efficiency and stable charge and discharge even in long-term use.

Provided is an electrolyte membrane including at least the following: an A-layer composed of an ion-conducting fluorinated polymer and a non-ion-conducting fluorinated polymer; and a B-layer composed of an ion-conducting hydrocarbon polymer, wherein the ion-conducting hydrocarbon polymer is dispersed in the A-layer. Provided is an electrolyte membrane having excellent oxidation resistance. In addition, provided is an electrolyte membrane for a redox-flow battery, in which the electrolyte membrane used as a barrier membrane for a redox-flow battery makes it possible to achieve high power efficiency and stable charge and discharge even in long-term use.

Provided are a composite that can be suitably used as an electrolyte for polymer-based solid-state batteries and is excellent in oxidation resistance and flame retardancy, and various electrochemical devices using such a composite. The composite contains a fluorine-containing copolymer that comprises a tetrafluoroethylene (TFE) unit and a vinylidene fluoride (VdF) unit, and an alkali metal salt, wherein the total content of the TFE unit and the VdF unit in the fluorine-containing copolymer is 1 to 99 mol %, and the composite has a volatile content of 0.1 mass % or less with respect to the entire composite.

A new polyelectrolyte multilayer coated proton-exchange membrane for electrolysis and fuel cell applications has been developed for electrolysis and fuel cell applications. The polyelectrolyte multilayer coated proton-exchange membrane comprises: a cation exchange membrane, and a polyelectrolyte multilayer coating on one or both surfaces of the cation exchange membrane. The polyelectrolyte multilayer coating comprises alternating layers of a polycation polymer and a polyanion polymer. The polycation polymer layer is deposited on and is in contact with the cation exchange membrane. The top layer of the polyelectrolyte multilayer coating can be either a polycation polymer layer or a polyanion polymer layer.

A polyelectrolyte multilayer membrane has been developed for redox flow batteries and other electrochemical reaction applications. The polyelectrolyte multilayer membrane comprises an ionically conductive thin film composite membrane comprising a microporous support membrane, a hydrophilic ionomeric polymer coating layer on the surface of the microporous support membrane, and a polyelectrolyte multilayer coating on the second surface of the hydrophilic ionomeric polymer coating layer (the side opposite the support membrane). The polyelectrolyte multilayer coating comprises alternating layers of a polycation polymer and a polyanion polymer. Methods of making the polyelectrolyte multilayer membrane and redox flow battery system including the polyelectrolyte multilayer membrane are also described.