PURPOSE: To manufacture a sintered nickel board with high porosity from 90∼ 95% and thereby improve capacity density of an electrode by specifying a volume of carbonyl nickel powder contained in a nickel slurry.

CONSTITUTION: A nickel slurry formed by a mixture of carbonyl nickel powder and an aqueous solution of organic high polymer such as carboxy methyl cellulose or methyl cellulose is applied to both surfaces of a porous metal core and dried, and thereafter sintered in an non-oxidizable atmosphere to prepare a nickel board. The board is filled with an active material. Upon manufacturing such a sintered electrode, a volume of the carbonyl powder in said slurry is made 2∼ 6%. In this case, sintering of the slurry is preferably performed at temperature in 800∼950°C. Hereby, a sintered nickel board with 90% or more of porosity, which can not be manufactured so far even with a loose sintering method, can be manufactured by an industrial slurry method, enabling high capacity density electrode to be yielded.