Method of producing lattice body for lead storage battery, and lead storage battery
A method of producing a grid for a lead-acid battery in accordance with the present invention includes the step of placing lead alloy foil on a base material sheet of a lead-calcium alloy and attaching the lead alloy foil under pressure to the base material sheet. The thickness t of the lead alloy foil, the thickness a of the base material sheet before the attaching, and the thickness b of the composite sheet after the attaching satisfy the relational expression 1.3≦(a+t)/b. The length L of the contact part of rollers with the base material sheet and the lead alloy foil is 10 mm or more. This makes it possible to secure good adhesion of the lead alloy foil to the base material sheet. Also, when this composite sheet is subjected to an expanding process and used as a positive electrode grid, it is possible to provide a lead-acid battery having excellent cycle life characteristics.
1. A method of producing a grid for a lead-acid battery, comprising the steps of:
(1) passing lead alloy foil together with a base material sheet of a lead-calcium alloy between a pair of rollers to attach the lead alloy foil to the base material sheet, to make a composite sheet, and
(2) passing the composite sheet between a plurality of pairs of rollers to gradually roll said composite sheet to a predetermined thickness after said step (1),
wherein the thickness t (mm) of the lead alloy foil, the thickness a (mm) of the base material sheet, the thickness b (mm) of the composite sheet before said step (2), and the radius r (mm) of the roller in said step (1) satisfy the relational expressions:
1.3≦( a+t )/ b , and
10 ≦r ·cos −1 [1−{( a+t−b )/2 r} ].
2. The method of producing a grid for a lead-acid battery in accordance with claim 1 , wherein the temperature difference between the base material sheet and the lead alloy foil is 50° C. or less in said step (1).
3. The method of producing a grid for a lead-acid battery in accordance with claims 1 or 2 , wherein the lead alloy foil comprises a lead alloy containing at least one selected from the group consisting of Sn, Sb and Ag.
4. The method of producing a grid for a lead-acid battery in accordance with claim 1 , further comprising the step (3) of subjecting the composite sheet to an expanding process after said step (2).
5. A lead-acid battery using a lead-acid battery grid obtained by the production method of claim 4 as at least a positive electrode grid.