A method of protecting a nonoperational CO.sub.2 electrolysis stack from corrosion, includes: at least partly emptying an electrolyte from parts of a first electrolysis cell and/or of a first feed and/or of a first drain and/or of an overall feed which is connected to the first feed and the second feed and is designed to provide an inlet for the first feed and the second feed and/or of an overall drain which is connected to the first drain and the second drain and is designed to provide an outlet for the first drain and the second drain. The electrolyte which is removed by the at least partial emptying is exchanged for an inert gas or a mixture including an inert gas and liquid droplets present therein, wherein the inert gas is CO.sub.2.

To make it possible to detect a short circuit in a water electrolyzer even while the water electrolyzer is operating, a voltage sensor is disposed for each of plural water electrolytic cells, the voltage of each of the water electrolytic cells is measured with the voltage sensor while the water electrolyzer is operating, and it is determined that there is a short circuit if it is detected that the voltage is lower than a reference voltage.

A process for preparing or regenerating peroxodisulfuric acid and its salts by electrolysis of an aqueous solution containing sulfuric acid and/or metal sulfates at diamond-coated electrodes without addition of promoters is described, with bipolar silicon electrodes which are coated with diamond on one side and whose uncoated silicon rear side serves as cathode being used.

Described herein are systems and methods for the management and control of electrolyte within confined electrochemical cells or groups (e.g. stacks) of connected electrochemical cells, for example, in an electrolyzer. Various embodiments of systems and methods provide for the elimination of parasitic conductive paths between cells, and/or precise passive control of fluid pressures within cells. In some embodiments, a fixed volume of electrolyte is substantially retained within each cell while efficiently collecting and removing produced gases or other products from the cell.

A system and method for treating flue gas of a boiler based on solar energy are provided, wherein a heat pump is connected with a heat collector via first and second valves, a carbon dioxide electrolysis chamber is connected with a flue gas pretreatment chamber and a power distribution control module for electrolyzing and reducing carbon dioxide, a gas phase separation chamber is connected with a gas phase outlet to separate a mixture, and discharge the separated gas phase products; a Fischer-Tropsch reaction chamber is connected with the gas phase separation chamber to pass the separated carbon monoxide and hydrogen into a flowing reaction cell, a liquid phase product separation chamber is connected with a liquid phase outlet to separate the liquid phase hydrocarbon fuel products, and separate and supplement electrolyte; an electrolyte cooling circulation chamber is connected with the liquid phase product separation chamber.

A cell stack includes a plurality of single cells, wherein each single cell includes a membrane electrode assembly having a cathode, an anode, an interposed membrane, and an anode gas diffusion layer wherein a) in a single cell, the anode gas diffusion layer and a cathode gas diffusion layer are arranged in relation to one another such that a first thickness gradient of the anode gas diffusion layer and a second thickness gradient of the cathode gas diffusion layer run opposite to one another or b) in two or more single cells, the anode gas diffusion layers are arranged in relation to one another such that an overall thickness gradient of the anode gas diffusion layers is minimized and/or wherein in two or more single cells, the cathode gas diffusion layers are arranged such that an overall thickness gradient of the cathode gas diffusion layers is minimized.

An electrolytic cell may include a cathode half-cell having a cathode, an anode half-cell having an anode, and a separator that separates the two half-cells from one another and that is permeable to electrolyte present in the half-cells during operation. At least one inlet for electrolyte is provided in a first half-cell of the two half-cells, and at least one outlet for electrolyte and no inlet for electrolyte are provided in the second half-cell such that electrolyte supplied via the at least one inlet is dischargeable via the at least one outlet after passing through the separator. A method can also be utilized to operate such an electrolytic cell. And an electrolyzer may include multiple of such electrolytic cells.

The present invention relates to a method for producing hydrogen in a polymer electrolyte membrane (PEM) water electrolyser cell. A direct electric current is applied to the water electrolyser cell. Water molecules are allowed to diffuse from a cathode compartment through a polymer electrolyte membrane into an anode compartment, to oxidize water molecules at an anode catalyst layer into protons, oxygen and electrons. The protons are allowed to migrate through a polymer electrolyte membrane into the cathode compartment and the protons are reduced at a cathode catalyst layer to produce hydrogen. The cell is supplied with water to the cathode compartment, and humidified air is supplied to the anode compartment. The invention also relates to a polymer electrolyte membrane (PEM) water electrolyser cell, a polymer electrolyte membrane (PEM) water electrolyser stack and a polymer electrolyte membrane (PEM) water electrolyser system.

The present invention relates to a method for producing hydrogen in a polymer electrolyte membrane (PEM) water electrolyser cell. A direct electric current is applied to the water electrolyser cell. Water molecules are allowed to diffuse from a cathode compartment through a polymer electrolyte membrane into an anode compartment, to oxidize water molecules at an anode catalyst layer into protons, oxygen and electrons. The protons are allowed to migrate through a polymer electrolyte membrane into the cathode compartment and the protons are reduced at a cathode catalyst layer to produce hydrogen. The cell is supplied with water to the cathode compartment, and humidified air is supplied to the anode compartment. The invention also relates to a polymer electrolyte membrane (PEM) water electrolyser cell, a polymer electrolyte membrane (PEM) water electrolyser stack and a polymer electrolyte membrane (PEM) water electrolyser system.

Electrochemical systems comprising separator plates and the separator plates comprising a first individual plate and a second individual plate. The individual plate comprising: an electrochemically active region, at least one through-opening and a sealing bead. Conveying channels adjoin a bead flank of the sealing bead and the conveying channels connecting the through-opening and the sealing bead interior. A plurality of first weld sections connecting the two individual plates and the first weld sections extend in the direction of the first conveying channels and arranged between the first conveying channels.