A dimeric ionic liquid that enhances and improves the performance and durability of a fuel cell catalyst. The dimeric ionic liquid comprises 1,1-(butane-1,4-diyl)bis(9-methyl-3,4,6,7,8,9-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-ium 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate (D-[MTBD][C.sub.4F.sub.9SO.sub.3]). Membrane electrode assemblies (MEAs) and polymer electrolyte membrane fuel cells (PEMFCs) employing the dimeric ionic liquid are also disclosed.

An object of the present invention is to provide a membrane for a redox flow battery which is prevented from being curled and exhibits high power efficiency, a membrane electrode assembly for a redox flow battery, a cell for a redox flow battery, and a redox flow battery. The object can be attained by a membrane for a redox flow battery, comprising a first ion-exchange resin layer, an anion-exchange resin layer containing an anion-exchange compound, and a second ion-exchange resin layer in the presented order, wherein a value obtained by dividing a thickness of the first ion-exchange resin layer by a thickness of the second ion-exchange resin layer is 0.7 or more and 1.3 or less, and a thickness of the anion-exchange resin layer is 0.02 μm or larger and 3 μm or smaller.

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.

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.

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.

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.

An electrochemical cell includes a fuel source; an oxidation source; a positive electrode exposed to an electrolyte membrane; a negative electrode exposed to the electrolyte membrane; and the electrolyte membrane positioned between the positive and negative electrodes, the electrolyte membrane including an electron donor material and a shunt material having specific volume percentage of one or more carbon-containing semiconductors that become electronically conductive at a specific shunting onset potential below the cell's open circuit potential.

An electrochemical cell includes a fuel source; an oxidation source; a positive electrode exposed to an electrolyte membrane; a negative electrode exposed to the electrolyte membrane; and the electrolyte membrane positioned between the positive and negative electrodes, the electrolyte membrane including an electron donor material and a shunt material having specific volume percentage of one or more carbon-containing semiconductors that become electronically conductive at a specific shunting onset potential below the cell's open circuit potential.

A composite electrolyte membrane having a composite layer that is a composite of a hydrocarbon polymer electrolyte and a fluorine-containing polymer porous substrate, wherein a fractal dimension D exhibiting the distribution of the hydrocarbon polymer electrolyte and the fluorine-containing polymer porous substrate in the composite layer is 1.7 or more. An object of the present invention is to enable a composite electrolyte membrane composed of a hydrocarbon polymer electrolyte and a fluorine-containing polymer porous substrate to achieve high proton conduction ability and high mechanical durability.