Among the various aspects of the present disclosure is the provision of method of inducing or providing a pH gradient in electrochemical or chemical systems. Briefly, the pH gradient is induced by use of coated particles or films with an ion exchange ionomer.

A method and system for releasably storing hydrogen and generating electricity including an electrochemical cell including a cathode, an anode, an electrolyte, a microporous separator, an electrical connection between the cathode and the anode, an amine source, a nitrile source, a hydrogen source, and an oxygen source, wherein the electrochemical cell is configured to be operated in a hydrogen storage mode, a hydrogen release mode, and electrical generation mode. The amine/nitrile redox couple provides for full cycle electrochemical conversion of hydrogen under mild conditions.

The invention relates to the field of alkaline electrochemical cells and more specifically to that of batteries. More specifically, the invention pertains to a secondary electrochemical cell with a zinc electrode, which is differentiated in that it comprises: a) an electrolyte which is an alkaline aqueous solution whose molarity is between 4 M and 15 M hydroxyl anions, comprising soluble silicates whose concentration expressed as silica (SiO.sub.2) is between 0.15 g/l and 80 g/l; and b) a zinc electrode containing a conductive ceramic at least partly consisting of hafnium nitride and/or carbide and/or magnesium carbide and/or nitride and/or silicide and/or niobium carbide and/or nitride and/or titanium carbide and/or nitride and/or silicide and/or vanadium nitride acid/or of double carbides and/or nitrides of any two metals selected among hafnium, magnesium, niobium, titanium and vanadium.

Alkaline electrochemical cells are provided, containing cathodes with a nickel compound active material, wherein active material particles are coated with at least one of a number of materials so as to improve the shelf life of the electrochemical cell. Methods of preparing such cathodes and electrochemical cells are also provided.

A negative electrode active material for aqueous secondary batteries, said negative electrode active material being applied to an aqueous secondary battery that uses an aqueous electrolyte solution containing water and a lithium salt, wherein: the negative electrode active material contains graphite; the graphite has a C—F bond group on the surface; if I.sub.688eV is the peak intensity at around 688 eV ascribed to a C—F bond and I.sub.284eV is the peak intensity at around 284 eV ascribed to a C—C bond in the XPS spectrum of the graphite as obtained by X-ray photoelectron spectroscopy, the ratio of the peak intensity I.sub.688eV to the peak intensity I.sub.284eV (namely, the value of I.sub.688eV/I.sub.284eV ) is from 0.1 to 7; and the BET specific surface area is from 0.5 m.sup.2/g to 3.9 m.sup.2/g.

A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.

An alkaline dry battery includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an alkaline electrolytic solution contained in the positive electrode, the negative electrode and the separator. The negative electrode includes a negative electrode active material including zinc, and an additive. The additive includes at least one selected from the group consisting of maleic acid, maleic anhydride and maleate salts.

According to one embodiment, a secondary battery (100) including a positive electrode (5), a negative electrode (3), a first electrolyte (9), and a second electrolyte (8). The negative electrode (3) includes a lithium titanium oxide having a degree of proton substitution of 0.01 to 0.2. The first electrolyte (9) includes water and in contact with the positive electrode (5). The second electrolyte (8) includes water and in contact with the negative electrode (3).

An electrochemical system, the system including an aqueous electrolyte, at least one chelating agent configured to bind to at least one detrimental ionic species, and a particulate precipitation site. A method of forming an electrochemical system including creating a housing with an interior volume, placing at least one electrode within the interior volume, adding at least one chelating agent configured to bind to at least one detrimental ionic species into the interior volume, and adding a particulate precipitation site to the interior volume.

A redox flow battery includes a redox flow cell and a supply and storage system external of the redox flow cell. The supply and storage system includes first and second electrolytes for circulation through the redox flow cell. The first electrolyte is a liquid electrolyte having electrochemically active manganese species with multiple, reversible oxidation states in the redox flow cell. The electrochemically active manganese species may undergo reactions that cause precipitation of manganese oxide solids. The first electrolyte includes an inhibitor that limits the self-discharge reactions. The inhibitor includes an oxoanion compound.