To provide a convenient and effective method for suppressing the penetration of dendrite over the microporous film mainly containing the base portion, which occupies the most part of the entire separator (total area), rather than the peculiar concept (resulting in a difficult measure), in which only the pore structure of the rib portion is densified or contracted for suppressing dendrite from penetrating through the rib portion. A separator for a lead-acid battery, containing a microporous film obtained in such a manner that a raw material composition mainly containing a polyolefin resin, silica powder, and a plasticizer is melt-kneaded and formed into a film, from which the plasticizer is entirely or partially removed, the raw material composition containing glass flakes having an average particle diameter of from 20 to 800 m and an average thickness of 0.2 to 8 m and having no self-film formability in an amount of from 2 to 15% by weight based on a total amount of the silica powder and the glass flakes, the glass flakes in the microporous film being disposed in such a manner that a plane direction thereof is substantially oriented in a plane direction of the microporous film, a value of (the content of the glass flakes in the microporous film)/(the average thickness of the glass flakes in the microporous film) being 1 or more.

To provide a convenient and effective method for suppressing the penetration of dendrite over the microporous film mainly containing the base portion, which occupies the most part of the entire separator (total area), rather than the peculiar concept (resulting in a difficult measure), in which only the pore structure of the rib portion is densified or contracted for suppressing dendrite from penetrating through the rib portion. A separator for a lead-acid battery, containing a microporous film obtained in such a manner that a raw material composition mainly containing a polyolefin resin, silica powder, and a plasticizer is melt-kneaded and formed into a film, from which the plasticizer is entirely or partially removed, the raw material composition containing glass flakes having an average particle diameter of from 20 to 800 m and an average thickness of 0.2 to 8 m and having no self-film formability in an amount of from 2 to 15% by weight based on a total amount of the silica powder and the glass flakes, the glass flakes in the microporous film being disposed in such a manner that a plane direction thereof is substantially oriented in a plane direction of the microporous film, a value of (the content of the glass flakes in the microporous film)/(the average thickness of the glass flakes in the microporous film) being 1 or more.

Lead-acid batteries with low water consumption and hydrogen gassing, comprise electrodes of a carbon fibre material having a surface area of less than 50 m.sup.2/g. The carbon fibre material may also comprise non-carbon functional groups less than 22% by mass in the bulk fibre, and at least 78% carbon by mass in the bulk fibre. The carbon fibre material may be heated to a temperature of at least 1000 C. and cooled in an inert atmosphere to prevent non-carbon functional groups reforming on the carbonised carbon fibre material. The batteries are suitable for use in hybrid vehicles.

Lead-acid batteries with low water consumption and hydrogen gassing, comprise electrodes of a carbon fibre material having a surface area of less than 50 m.sup.2/g. The carbon fibre material may also comprise non-carbon functional groups less than 22% by mass in the bulk fibre, and at least 78% carbon by mass in the bulk fibre. The carbon fibre material may be heated to a temperature of at least 1000 C. and cooled in an inert atmosphere to prevent non-carbon functional groups reforming on the carbonised carbon fibre material. The batteries are suitable for use in hybrid vehicles.

In a bipolar storage battery where a positive electrode current collector plate and a negative electrode current collector plate are electrically connected in a through-hole of a substrate and a plurality of cell members are electrically connected in series, even when an electrolytic solution moves between the current collector plate and the substrate, the electrolytic solution is prevented from easily reaching the through-hole of the substrate, preventing a short circuit. At least one of a bottom surface of a recess that is a surface of a main substrate close to a positive electrode or a bottom surface of a recess that is a surface of the main substrate close to a negative electrode, the main substrate being a substrate arranged between cell members, has a ten-point average roughness (RzJIS) of between 30 ?m and 104 ?m, inclusive, and a maximum height roughness (Rz) of 123 ?m or less.

In a bipolar storage battery where a positive electrode current collector plate and a negative electrode current collector plate are electrically connected in a through-hole of a substrate and a plurality of cell members are electrically connected in series, even when an electrolytic solution moves between the current collector plate and the substrate, the electrolytic solution is prevented from easily reaching the through-hole of the substrate, preventing a short circuit. At least one of a bottom surface of a recess that is a surface of a main substrate close to a positive electrode or a bottom surface of a recess that is a surface of the main substrate close to a negative electrode, the main substrate being a substrate arranged between cell members, has a ten-point average roughness (RzJIS) of between 30 ?m and 104 ?m, inclusive, and a maximum height roughness (Rz) of 123 ?m or less.

A lead-acid battery includes an electrode plate assembly, a battery case, a positive electrode strap, a negative electrode strap, a positive electrode post, a negative electrode post, a cover, and an electrolyte solution. A negative electrode bushing provided in the cover and the negative electrode post together constitute a negative electrode terminal. A maximum value of a gap between an outer circumferential surface of the negative electrode post and an inner circumferential surface of the negative electrode bushing in the negative electrode terminal is 0.5 mm or more and 2.5 mm or less. A rib is provided in a lower part of the negative electrode bushing, and a minimum value of a protrusion height of the rib is 1.5 mm or more and 4.0 mm or less. A distance between a surface of the electrolyte solution and a lowermost portion of the negative electrode bushing is 15 mm or less.

A lead acid battery including: a positive electrode plate including a positive electrode grid and a positive electrode active material; a negative electrode plate including a negative electrode grid and a negative electrode active material; an electrode plate group including the positive electrode plate, the negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate; a battery container including a plurality of cell chambers each accommodating the electrode plate group and an electrolyte; and a lid sealing an opening of the battery container. A ratio P/N of mass P of the positive electrode active material to mass N of the negative electrode active material is 1.25 or more and 1.65 or less. The negative electrode grid contains bismuth in an amount of 1 ppm or more and 300 ppm or less.

A lead acid battery including: a positive electrode plate including a positive electrode grid and a positive electrode active material; a negative electrode plate including a negative electrode grid and a negative electrode active material; an electrode plate group including the positive electrode plate, the negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate; a battery container including a plurality of cell chambers each accommodating the electrode plate group and an electrolyte; and a lid sealing an opening of the battery container. A ratio P/N of mass P of the positive electrode active material to mass N of the negative electrode active material is 1.25 or more and 1.65 or less. The negative electrode grid contains bismuth in an amount of 1 ppm or more and 300 ppm or less.

A nano-coating material, capable of being bonded to the surface of a metal or an alloy substrate, the nano-coating material includes a compound having, in a polymer main chain, (A) a first side chain or a terminal, each having a binding group containing a benzene ring having at least one pair of adjacent hydroxyl groups; and (B) a functional second side chain.