Disclosed are electrochemical cells and methods of use or operation at high pressure, in which one or more gas-producing electrodes operate in a manner that is bubble-free or substantially bubble-free. Disclosed is a method for producing a gas in an electrochemical cell, and the electrochemical cell itself, wherein the electrochemical cell comprises a gas-producing electrode and a counter electrode being separated by an electrolyte. The method comprises creating an electrolyte pressure greater than or equal to 10 bar during operation of the electrochemical cell, and producing the gas wherein substantially no bubbles of the gas are formed at the gas-producing electrode. Preferably, there is no diaphragm or ion exchange membrane positioned between the gas-producing electrode and the counter electrode. In another example, the electrochemical cell is operated without a gas compressor. The gas-producing electrode and/or the counter electrode is a gas diffusion electrode.

Disclosed are electrochemical cells and methods of use or operation, in which one or more gas-producing electrodes operate in a manner that is bubble-free or substantially bubble-free. Disclosed are electrochemical cells and methods of operation or use under conditions of intermittent and/or fluctuating currents. In one aspect there is provided a method for operating an electrochemical cell, and an electrochemical cell, wherein the electrochemical cell comprises: a gas-producing electrode; a counter electrode, the gas-producing electrode and the counter electrode being separated by an electrolyte. Preferably there is also provided one or more void volumes. The method comprises: supplying an intermittent and/or fluctuating current to at least the gas-producing electrode; and producing a gas at the gas-producing electrode as a result of an electrochemical reaction. Preferably the gas is received by the one or more void volumes.

Disclosed are electrochemical cells and methods of operation. In one aspect is disclosed an electrochemical cell that has a liquid-electrolyte or a gel-electrolyte, the cell comprising: an electrode, preferably a gas diffusion electrode; a busbar attached to a current collector of the electrode; and a second electrode to which the first electrode is connected in electrical series. In another aspect is disclosed a plurality of electrochemical cells, comprising: a first electrochemical cell comprising a first cathode and a first anode, wherein at least one of the first cathode and the first anode is a gas diffusion electrode; a second electrochemical cell comprising a second cathode and a second anode, wherein at least one of the second cathode and the second anode is a gas diffusion electrode; wherein, the first cathode is electrically connected in series to the second anode by an electron conduction pathway.

Energy storage devices comprising carbon-based electrodes comprising energy-dense faradaic materials and oxidation-reduction (redox) electrolytes are disclosed. In some embodiments, the carbon-based electrodes comprise energy-dense magnetite nanoparticles. In some embodiments, the redox electrolytes comprise ferricyanide/ferrocyanide redox couple. Also described are processes, methods, protocols, and the like for manufacturing carbon-based electrodes comprising magnetite nanoparticles for use in high energy storage devices such as supercapacitors and for manufacturing high energy storage devices comprising redox electrolytes.

A method for manufacturing a metal plate including a rolling step for rolling a metal material provided with a penetration space passing through the metal material in a thickness direction to reduce the thickness of the metal material and reduce the area of a surface opening formed in the surface of the metal material by the penetration space, thereby producing a plate-like metal plate.

Disclosed are fuel cell stack break-in procedures, conditioning systems for performing break-in procedures, and motor vehicles with a fuel cell stack conditioned in accordance with disclosed break-in procedures. A break-in method is disclosed for conditioning a membrane assembly of a fuel cell stack. The method includes transmitting humidified hydrogen to the anode of the membrane assembly, and transmitting deionized water to the cathode of the membrane assembly. An electric current and voltage cycle are applied across the fuel cell stack while the fuel cell stack is operated in a hydrogen pumping mode until the fuel cell stack is determined to operate at a predetermined threshold for a fuel cell stack voltage output capability. During hydrogen pumping, the membrane assembly oxidizes the humidified hydrogen, transports protons from the anode to the cathode across the proton conducting membrane, and regenerates the protons in the cathode through a hydrogen evolution reaction.

A regenerative fuel cell produces hydrogen that is stored in a reservoir on the storage side of a membrane electrode assembly when operating in a hydrogen pumping mode and this stored hydrogen is reacted and moved back through the membrane electrode assembly to form water when operating in a fuel cell mode. A metal hydride forming alloy may be configured in the hydrogen storage reservoir and may be coupled to the membrane electrode assembly. An integral metal hydride electrode having a metal hydride forming alloy may be configured on the storage side of the membrane electrode assembly and may have a catalyst or an ion conductive media incorporated therewith.

The present invention relates to a monopropellant system for a regenerative fuel cell (RFC) and a method for mono-propulsion using same and, more specifically, to a monopropellant system for an RFC which can, when operating an electrically propelled airplane adopting an RFC system, secure more energy via a monopropellant than conventional methods and use same as a propulsion source for airplane takeoff and so on, and to a method for mono-propulsion using the monopropellant system for an RFC.

A novel electrochemical cell is disclosed in multiple embodiments. The instant invention relates to an electrochemical cell design. In one embodiment, the cell design can electrolyze water into pressurized hydrogen using low-cost materials. In another embodiment, the cell design can convert hydrogen and oxygen into electricity. In another embodiment, the cell design can electrolyze water into hydrogen and oxygen for storage, then later convert the stored hydrogen and oxygen back into electricity and water.

An electrochemical cell system and a method for operating an electrochemical cell is provided. The method including determining one of a power level, current level or a voltage level of the electrochemical cell, the electrochemical cell including at least one cell having an anode side and a cathode side, the electrochemical cell further having a water transport plate operably coupled to the cathode side. An oxidant pressure level is determined in the cathode side. A water pressure level is determined in the water transport plate. The active area of the at least one cell is changed by adjusting at least one of the oxidant pressure level or the water pressure level based at least in part on the determined power level, current level or voltage level.