PURPOSE: To increase the utilization factor of an active material contained in a plate, and enhance the energy density of a lead-acid battery without causing any drop in plate strength and battery service life.

CONSTITUTION: 1wt.% of a porous material (wooden pieces through 32-mesh sieve) is added to active material paste. A current collector of grating shape is filled with a product so made, up to 2mm thickness for the finished plate thickness of 3mm. Then, the remaining space of 1mm is filled with ordinary active material paste without any porous material, and a plate has an active material as an inner layer.