Dowa Mining Co., Ltd.

Kenichi Harigae

Kouki Toishi

Hidekazu Kato

Shigetoshi Uchino

Choju Nagata

Yoshiyuki Shoji

Akinobu Iikawa

Masaru Nishisako

Yuichi Ito

Yukio Hiraoka

A silver oxide powder that replaces silver powder as a silver conductive paste filler has a specific surface area measured by the BET method is 1.0&#x2013;25.0 m/g, average primary particle diameter is 1&#x2013;50 nm, and average secondary particle diameter is 1&#x2013;1000 nm. The silver oxide powder is made by preparing a neutralization medium that is an aqueous solution containing one or both of sodium hydroxide and potassium hydroxide in a total amount of 0.5 mole/L or less, simultaneously adding an aqueous solution containing silver salt in an amount of 6.0 mole/L or less and an aqueous solution of at least one of sodium hydroxide and potassium hydroxide to the liquid medium to conduct a neutralization reaction, thereby obtaining a neutralized precipitate, maintaining the liquid at a pH in the range of 12&#xb1;1.5 during the reaction, and subjecting the precipitate to filtration, washing, and drying.

Fine-grain silver oxide powder

An aqueous sodium carbonate solution is added in an equivalent amount to an aqueous silver nitrate solution (Ag=100 g/L) under stirring and, with nitric acid and sodium hydroxide being added to adjust the pH to 5.5-6.5, a silver carbonate precipitate is formed and subsequently washed thoroughly and dried at 250.degree. C. or below to produce a silver oxide powder, which satisfactory characteristics for use in cells, as exemplified by high water absorption, good shape of granules, high strength, non-stickiness to the molding punch, high fluidity and low residual carbon content. The pellet of the powder has high cell capacity.

Silver oxide for use in cells and a process for producing the same

The mixed powders of a lithium compound and a transition metal based compound are formed into shaped parts, which are packed to form a bed 6 on a porous plate 5 in the bottom of a reaction vessel 7 placed on a support 10 in a firing furnace 8 equipped with an electric heater; the packed parts are fired with an oxidizing gas such as air being forced through the bed 6 at a superficial velocity higher than a specified value via a gas feed pipe 3 connecting an air pump 1, a flow regulator 2 and a preheater 4 and the gas emerging from the bed 6 is discharged into the air atmosphere through a ventilation port 9. Even if increased amounts of the mixed powders have to be fired, the invention process enables the production of a lithium complex oxide as an active material that is homogeneous and which features excellent cell characteristics. If the manufacturing conditions are controlled such that the media diameter as a powder characteristic of the lithium complex oxide is within an appropriate range while, at the same time, the ratio of the median diameter to the specific surface area diameter is adjusted to lie within an appropriate range, one can produce an active material that has not only high initial capacity but also improved cycle characteristics.

Positive electrode active material for nonaqueous secondary cells and a

Growing community of inventors

Honjo, Japan

Kenichi Harigae