Sumitomo Metal Mining Company, Ltd.

Minoru Shiraoka

Ryuichi Kuzuo

Katsuya Kase

Hideo Sasaoka

A method for producing coated nickel hydroxide powder for a positive electrode of an alkaline secondary battery wherein the pH of a suspension of a nickel hydroxide powder is kept at 8 to 11.5, and an aqueous cobalt salt solution and an aqueous alkali solution are supplied to the suspension to coat the surface of nickel hydroxide particles with cobalt hydroxide. Then, the pH of a slurry of the cobalt hydroxide-coated nickel hydroxide powder is adjusted to 12.5 to 13.0, and oxygen is supplied to the slurry so that the total amount of oxygen supplied per mole of cobalt in the coating is 30 l/mol or more to oxidize the cobalt hydroxide.

Coated nickel hydroxide powder for positive electrode active material for alkaline secondary battery, and production method therefor

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&#x2212;B)/(B&#x2212;B). The transmittance A (coated nickel hydroxide powder), the transmittance B(nickel hydroxide powder), or the transmittance B(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.

Coated nickel hydroxide powder for positive electrode active material of alkaline secondary battery, and evaluation method for coating adhesion properties of coated nickel hydroxide powder

A coated nickel hydroxide powder suitable as a cathode active material for alkaline secondary battery includes nickel hydroxide powder particles which have a coating layer thereon of preferably cobalt hydroxide or cobalt oxyhydroxide.

Coated nickel hydroxide powder as cathode active material for alkaline secondary battery and method for producing same

A method for producing a coated nickel hydroxide powder suitable as a cathode active material for alkaline secondary battery includes the steps of: dispersing a nickel hydroxide powder in water to prepare a suspension, an aqueous alkali solution to the suspension with stirring to keep a pH of the suspension at 8 or higher as measured at 25&#xb0; C., and supplying an aqueous cobalt salt solution to the suspension to coat a surface of each particles of the nickel hydroxide powder with cobalt hydroxide crystallized out by neutralization.

Growing community of inventors

Ehime, Japan

Minoru Shiraoka