TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The group (I) in monomer (A) is a 1-18C alkoxy carbonyl group. Monomer (A) is an alkyl acrylic acid ester and/or an alkyl methacrylic acid ester. Monomer (B) is aromatic hydrocarbon with two vinyl groups and/or an aliphatic hydrocarbon with two vinyl groups and fluorine atoms(s). The electrolyte layer further comprises a water repellent material comprising fluorinated carbon and/or fluorocarbon resin, a core comprising a non-woven or woven fabric sheet comprising polyolefin or polyamide and an additive comprising polyethylene, polypropylene, carboxymethyl cellulose, styrene butadiene rubber and/or polyvinyl alcohol. The amount of water absorbent polymer contained in electrolyte layer is 1-20 g/m2.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Battery: The electrolyte layer is in intimate contact with surface of positive electrode and/or negative electrode. The electrolyte layer has thickness of 20-200 micrometers. The negative electrode comprises a hydrogen storage alloy. EXAMPLE - Methyl acrylate (in g) (70), sodium styrene sulfonate (3), divinyl benzene (3.7), potassium peroxosulfate (1.5) and water (550) were mixed. The mixture was heated with stirring to 70 degrees C for 8 hours under a nitrogen gas atmosphere to polymerize methyl acrylate and divinyl benzene. The resultant copolymer was immersed in a mixed solution comprising methanol (51 wt.%), water (34 wt.%) and potassium hydroxide (15 wt.%), and the solution was allowed to stand at 65 degrees C for 2 hours to saponify the copolymer. The saponified copolymer was washed with methanol, dried and pulverized to produce a water absorbent polymer. The obtained water absorbent polymer (10) was mixed with a potassium hydroxide aqueous solution (125) with a specific gravity of 1.25 g/cm3 and carboxymethyl cellulose (0.1), followed by gelation. The resultant gel was applied to a non-woven fabric sheet comprising sulfonated polypropylene and then dried to produce an electrolyte layer. The amount of water absorbent polymer contained in the electrolyte layer was 6 g/m2. A positive electrode containing nickel hydroxide containing cobalt and zinc as positive electrode active material and a negative electrode containing AB5 type hydrogen storage alloy as negative electrode material, were laminated, with the electrolyte layer comprising a water absorbent polymer interposed between the electrodes and spirally wound to form an electrode assembly. An insulating plate was disposed at the bottom portion of the electrode assembly and the whole structure was placed in an AA-size case. Subsequently, a potassium hydroxide aqueous solution with a specific gravity of 1.3 g/cm3 was injected into the case as an electrolyte. Then, an insulating plate was placed on the top of the electrode assembly. The opening of the case was sealed using a sealing plate with a positive electrode terminal and a safety valve and was provided with a gasket disposed at the peripheral portion. Prior to sealing the case, a positive electrode lead was connected to the sealing plate. The obtained battery had self-discharge rate of 23% and capacity recovery rate of 95%.