An air-water concentration cell is provided as follows. A cathode electrode is formed of a first material for catalyzing an oxygen reduction reaction (ORR). An anode electrode is formed of a second material for catalyzing an oxygen evolution reaction (OER). A proton conductive membrane is interposed between the cathode electrode and the anode electrode. A fuel reservoir is interposed between the proton conductive membrane and the anode electrode. The fuel reservoir contains water. The water of the fuel reservoir is in contact with the anode electrode and the proton conductive membrane.

An air-water concentration cell is provided as follows. A cathode electrode is formed of a first material for catalyzing an oxygen reduction reaction (ORR). An anode electrode is formed of a second material for catalyzing an oxygen evolution reaction (OER). A proton conductive membrane is interposed between the cathode electrode and the anode electrode. A fuel reservoir is interposed between the proton conductive membrane and the anode electrode. The fuel reservoir contains water. The water of the fuel reservoir is in contact with the anode electrode and the proton conductive membrane.

A manufacturing method and a manufacturing apparatus have high yields. The manufacturing method is a method for manufacturing a carbon fiber electrode substrate (3a) by feeding an oxidized fiber substrate (1a) through a carbonization furnace (102, 103) to carbonize the oxidized fiber substrate (1a). The method includes feeding, through the carbonization furnace (102, 103), a plurality of oxidized fiber substrates (1a) arranged in a thickness direction of the oxidized fiber substrates (1a).

A manufacturing method and a manufacturing apparatus have high yields. The manufacturing method is a method for manufacturing a carbon fiber electrode substrate (3a) by feeding an oxidized fiber substrate (1a) through a carbonization furnace (102, 103) to carbonize the oxidized fiber substrate (1a). The method includes feeding, through the carbonization furnace (102, 103), a plurality of oxidized fiber substrates (1a) arranged in a thickness direction of the oxidized fiber substrates (1a).

Herein discussed is a method of making a copper-containing electrode comprising: (a) forming a copper solution; (b) forming a ceramic substrate; (c) infiltrating the ceramic substrate with the copper solution; and (d) calcining the infiltrated substrate using electromagnetic radiation, wherein the substrate is no thicker than 50 microns. In an embodiment, the method comprises repeating (c) and (d) until copper percolates the ceramic substrate.

Herein discussed is a method of making a copper-containing electrode comprising: (a) forming a copper solution; (b) forming a ceramic substrate; (c) infiltrating the ceramic substrate with the copper solution; and (d) calcining the infiltrated substrate using electromagnetic radiation, wherein the substrate is no thicker than 50 microns. In an embodiment, the method comprises repeating (c) and (d) until copper percolates the ceramic substrate.

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.

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.

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.

An electrochemical cell may include: an anode; a porous anodic current collector; a cathode; a porous cathodic current collector; and an alkali metal-conducting separator that separates the anode from the cathode and is disposed surrounding the anodic current collector. The cathode may include seawater. A battery module may include a plurality of the electrochemical cells, and a battery may include a plurality of the battery modules.