A substrate for a composite membrane includes a microporous polyolefin membrane for carrying a hydrophilic resin compound within the pores of the microporous membrane wherein: the average pore diameter is 1 nm to 50 nm; the porosity is 50% to 78%; the membrane thickness is 1 μm to 12 μm; and, when a mixed solution of ethanol and water (volume ratio 1/2) is dripped onto a surface of the microporous polyolefin membrane which has not undergone hydrophilization treatment, the contact angle θ1 between the droplet and the surface is 0 to 90 degrees 1 second after the dripping, and the contact angle θ2 between the droplet and the surface is 0 to 70 degrees 10 minutes after the dripping, and the rate of change of the contact angle ((θ1−θ2)/θ1×100) is 10 to 50%.

Disclosed are a highly durable electrolyte membrane having improved ion conductivity and a method of producing the same. The electrolyte membrane may include an ionomer having hydrogen ion conductivity and a complex dispersed in the ionomer. The complex may include: a support; a primary antioxidant loaded on the support and having radical scavenging ability; and a secondary antioxidant loaded on the support and having peroxide decomposition activity.

The present invention provides a strong polymer electrolyte membrane which can provide a water electrolyzer operable at low electrolysis voltage. The polymer electrolyte membrane of the present invention comprises a fluorinated polymer and a woven fabric, wherein the weight of the woven fabric is from 20 to 95 g/m.sup.2, and the warp and weft of the woven fabric independently have a denier of from 30 to 100.

The present disclosure relates to an acid-base polymer blend membrane comprising at least one first polymer exhibiting acidic groups (A) and at least one second polymer exhibiting basic groups (B), wherein the molar ratio of acidic groups A / basic groups B in the acid-base polymer blend membrane is at least 1 / 0.25. Furthermore, the present disclosure relates to a cell membrane comprising a support structure and an acid-base polymer blend membrane, wherein the acid-base polymer blend membrane is impregnated on the support structure. Said cell membrane can be used in an electrodialysis cell, in a fuel cell, in a PEM electrolyzer, or in a redox flow battery, preferably in a redox flow battery.

The present disclosure relates to composite materials comprising a reinforcement material and a cationic polyelectrolyte, such as a porous reinforcement material impregnated with the cationic poly electrolyte. The present disclosure further relates to membrane electrode assemblies comprising the composites of the disclosure, and electrochemical devices comprising the disclosed membrane electrode assemblies.

Disclosed is a composite polymer electrolyte membrane comprising: a support membrane; a metal ion-blocking layer stacked on the support membrane; a stabilization layer; and a protecting layer, wherein the support membrane includes a cation conductive polymer.

A separation membrane for a redox flow battery includes: a protective film formed on each of both surfaces of a sheet substrate along with pores, the sheet substrate having thereon a number of pores communicating between the both surfaces; and an ion-exchange membrane adhered to the protective film, the ion-exchange membrane having a matrix formed of an ion-exchange resin dispersed therein with an inorganic porous powdery body attached with the ion-exchange resin obtained as a result of sulfonating rosin.

A separation membrane for a redox flow battery includes: a protective film formed on each of both surfaces of a sheet substrate along with pores, the sheet substrate having thereon a number of pores communicating between the both surfaces; and an ion-exchange membrane adhered to the protective film, the ion-exchange membrane having a matrix formed of an ion-exchange resin dispersed therein with an inorganic porous powdery body attached with the ion-exchange resin obtained as a result of sulfonating rosin.

A boron-containing proton-exchange solid support may include a proton-exchange solid support comprising an oxygen atom and a tetravalent boron-based acid group comprising a boron atom covalently bonded to the oxygen atom.

A proton exchange membrane includes a porous structural framework and a boron-based acid group bonded to the porous structural framework. The porous structural framework may be formed of an amorphous or crystalline inorganic material and/or a synthetic or natural polymer. The boron-based acid group may be a tetravalent boric acid derivative, such as a cyclic boric acid derivative, borospiranic acid, or a borospiranic acid derivative. The boron-based acid group may be the reaction product of boric acid or a boric acid derivative and a poly-hydroxy compound.