The present invention is directed to novel membrane electrode assemblies, and devices and systems incorporating them. Representative membrane electrode assemblies comprise (a) a first, porous electrode; (b) a buffer layer optionally comprising an aqueous solution comprising a pH buffer; (c) a membrane; and (d) a second, porous electrode comprising a catalyst for the generation of oxygen (02); wherein the membrane is interposed between the first electrode and the second electrode, and the buffer layer is interposed between the membrane and the first electrode.

According to one embodiment, there is provided a secondary battery including a negative electrode, a positive electrode, a first electrolyte, a second electrolyte, and a hydrogel electrolyte. The first electrolyte is in contact with at least a part of the negative electrode. The second electrolyte is in contact with at least a part of the positive electrode. The hydrogel electrolyte includes a gel having a chemically crosslinked structure. A first electrolyte composition of the first electrolyte is different from a second electrolyte composition of the second electrolyte. At least one of the first electrolyte and the second electrolyte includes an aqueous solvent, the aqueous solvent including water. At least a part of at least one of the negative electrode and the positive electrode overlaps at least a part of the hydrogel electrolyte.

This invention is directed to regeneration of solutions comprising metal ions, and production of valuable hydroxide compounds. Specifically, the invention is related to regeneration of spent electrolyte solutions comprising metal ions (e.g. Al ions), such as electrolyte solutions used in metal/air batteries. The invention is further related to production of layered double hydroxides, and, optionally aluminum tri-hydroxide from aluminate.

In various aspects, systems and methods are provided for operating a molten carbonate fuel cell, such as a fuel cell assembly, with increased production of syngas while also reducing or minimizing the amount of CO.sub.2 exiting the fuel cell in the cathode exhaust stream. This can allow for improved efficiency of syngas production while also generating electrical power.

A redox flow battery according to the present invention is provided with a battery module including a battery cell or a stack, and a pair of electrolyte tanks, and a replacement of a pump is applied for each battery module to transfer electrolyte to the battery cell and the stack such that shunt current is reduced. In addition, each battery module is provided with the pair of the electrolyte tanks such that a transfer distance of the electrolyte can be reduced, and a fluid controller using pressure instead of a pump for each module such that power required for driving the pump can be reduced and efficiency of the battery can be improved.

Methods and systems are provided for a rebalancing reactor of a flow battery system. In one example, a pH of a battery electrolyte may be maintained by the rebalancing reactor by applying a negative potential to a catalyst bed of the rebalancing reactor. A performance of the rebalancing reactor may further be maintained by treating the catalyst bed with deionized water.

A method of rebalancing electrolytes in a redox flow battery system comprises directing hydrogen gas generated on the negative side of the redox flow battery system to a catalyst surface, and fluidly contacting the hydrogen gas with an electrolyte comprising a metal ion at the catalyst surface, wherein the metal ion is chemically reduced by the hydrogen gas at the catalyst surface, and a state of charge of the electrolyte and pH of the electrolyte remain substantially balanced.

An anaerobic aluminum-water electrochemical cell that includes: a plurality of electrode stacks, each electrode stack comprising an aluminum or aluminum alloy anode, and at least one solid cathode configured to be electrically coupled to the anode; a liquid electrolyte between the anode and the at least one cathode; one or more physical separators between each electrode stack adjacent to the cathode; a housing configured to hold the electrode stacks, the electrolyte, and the physical separators; and a water injection port, in the housing, configured to introduce water into the housing. The electrolyte includes a hydroxide base at a concentration of at least 0.05 M to at most 3 M.

An anaerobic aluminum-water electrochemical cell that includes: a plurality of electrode stacks, each electrode stack featuring an aluminum or aluminum alloy anode, and at least one cathode configured to be electrically coupled to the anode; one or more physical separators between each electrode stack adjacent to the cathode; a housing configured to hold the electrode stacks, an electrolyte, and the physical separators; a water injection port, in the housing, configured to introduce water into the housing. The electrochemical cell also includes an amount of hydroxide base sufficient to form an electrolyte having a hydroxide base concentration of at least 0.05 M to at most 3 M when water is introduced between the anode and at least one cathode of the electrochemical cell. The aluminum or aluminum alloy of the anode is substantially free of titanium and boron.

An anaerobic aluminum-water electrochemical cell is provided. The electrochemical cell includes: a plurality of electrode stacks, each electrode stack including an aluminum or aluminum alloy anode, and at least one cathode configured to be electrically coupled to the anode; one or more physical separators between each electrode stack adjacent to the cathode; a housing configured to hold the electrode stacks, an electrolyte, and the physical separators; a water injection port, in the housing, configured to introduce water into the housing, and an amount of hydroxide base sufficient to form an electrolyte having a hydroxide base concentration of at least 0.5% to at most 13% of the saturation concentration when water is introduced between the anode and the least one cathode. The aluminum or aluminum alloy of the anode is substantially free of titanium and boron.