A battery 2 includes an outer can 10 and an electrode group 22 that is housed in the outer can 10 together with an alkaline electrolytic solution, in which a positive electrode 24 included in the electrode group 22 includes a positive electrode substrate and a positive electrode mixture supported on the positive electrode substrate, the positive electrode mixture includes nickel hydroxide and a positive electrode additive, the positive electrode additive includes a titanium oxide particle having an anatase-type crystal structure, the titanium oxide particle has an average primary particle size of 5 nm or more and 10 nm or less and a BET specific surface area of 230 m.sup.2/g or more and 360 m.sup.2/g or less, and includes 0.1% by mass or more of niobium, and a rate of addition of the titanium oxide relative to the nickel hydroxide is 0.1% by mass or more and 1.0% by mass or less.

A nickel-hydrogen secondary battery includes an electrode group comprising a separator, a positive electrode, and a negative electrode, and the positive electrode contains a positive electrode active material including a base particle comprising a nickel hydroxide particle containing Mn in solid solution and a conductive layer comprising a Co compound and covering the surface of the base particle, wherein the X-ray absorption edge energy of Mn detected within 6500 to 6600 eV by measurement with an XAFS method is 6548 eV or higher.

A nickel-hydrogen secondary battery includes an electrode group including a separator, a positive electrode, and a negative electrode, and the positive electrode includes a positive electrode active material particle including a base particle and a surface layer covering the surface of the base particle, and the base particle contains nickel hydroxide, and the surface layer contains a trivalent or higher-valent cobalt compound and Co.sub.3O.sub.4.

Provided is a secondary battery including a positive electrode, a negative electrode, an alkaline electrolytic solution, a separator structure exhibiting water impermeability and separating the positive electrode from the negative electrode, and a container accommodating at least the negative electrode and the alkaline electrolytic solution. The separator structure includes a porous substrate-supported ceramic separator, and a reinforcement having a lattice structure having openings and reinforcing the periphery and/or at least one surface of the porous substrate-supported ceramic separator. The porous substrate-supported ceramic separator includes a ceramic separator composed of an inorganic solid electrolyte having hydroxide ion conductivity in the form of a membrane or layer densified enough to have water impermeability, and a porous substrate disposed on at least one surface of the separator. The battery includes a porous substrate-supported ceramic separator with hydroxide ion conductivity having a high strength meeting an increase in the area of the separator.

Provided is a secondary battery including a hydroxide-ion-conductive ceramic separator. The secondary battery includes a positive electrode; a negative electrode; an alkaline electrolytic solution; a ceramic separator that is composed of a hydroxide-ion-conductive inorganic solid electrolyte and separates the positive electrode from the negative electrode; a porous substrate disposed on at least one surface of the ceramic separator; and a container accommodating at least the negative electrode and the alkaline electrolytic solution, wherein the inorganic solid electrolyte is in the form of a membrane or layer densified enough to have water impermeability, and the porous substrate has a thickness of 100 to 1,800 μm. According to the secondary battery of the present invention, the thickness and resistance of the ceramic separator are decreased without concern for reduced strength, and a reduction in energy density and an increase in internal resistance are effectively prevented.

A coated nickel hydroxide powder that has a cobalt compound coating having improved uniformity and adhesion properties on the surface of particles thereof and is therefore suitable for a positive electrode active material of an alkaline secondary battery is obtained by coating the surface of nickel hydroxide particles with a cobalt compound, and has a transmittance ratio of 30% or higher as determined by (A−B.sub.max)/(B.sub.0−B.sub.max). The transmittance A (coated nickel hydroxide powder), the transmittance B.sub.0 (nickel hydroxide powder), or the transmittance B.sub.max (nickel hydroxide powder and cobalt compound containing cobalt in an amount corresponding to the amount of cobalt contained in the coating) can be determined by measuring the transmittance of a tubular transparent cell after shaking the tightly-closed transparent cell containing each powder for a certain time and then taking the contents out of the transparent cell.

A coated nickel hydroxide powder that has a cobalt compound coating having improved uniformity and adhesion properties on the surface of particles thereof and is therefore suitable for a positive electrode active material of an alkaline secondary battery is obtained by coating the surface of nickel hydroxide particles with a cobalt compound, and has a transmittance ratio of 30% or higher as determined by (A−B.sub.max)/(B.sub.0−B.sub.max). The transmittance A (coated nickel hydroxide powder), the transmittance B.sub.0 (nickel hydroxide powder), or the transmittance B.sub.max (nickel hydroxide powder and cobalt compound containing cobalt in an amount corresponding to the amount of cobalt contained in the coating) can be determined by measuring the transmittance of a tubular transparent cell after shaking the tightly-closed transparent cell containing each powder for a certain time and then taking the contents out of the transparent cell.

The present invention relates to a metal-air electrochemical cell with a high energy efficiency mode.

The present invention relates to a metal-air electrochemical cell with a high energy efficiency mode.

A secondary battery according to an embodiment includes a container, an electrolytic solution, a cathode and an anode, and a flow mechanism. The container includes an opening on a bottom surface thereof. The electrolytic solution is disposed in the container. The cathode and the anode are disposed in the electrolytic solution. The flow mechanism includes a generation part that is connected to the container via the opening and generates a gas bubble(s) in the container through the opening, and that causes the electrolytic solution to flow. A protrusion part that is positioned at an edge part of the opening and extends in upward and downward directions is disposed on the bottom surface.