Cylindrical alkaline storage battery
An alkaline storage battery includes: a cylindrical case having a side wall including an opening end portion and a bottom; a sealing plate; a gasket interposed between the sealing plate and the opening end portion; and a sealant between the gasket and the opening end portion. The side wall has an annular groove opened at an outer surface thereof, and an inwardly curl portion at the opening end portion. In at least part of the groove, the minimum width L1 is within 0.2 mm. The sealant includes a polyamide resin formed such that when two test-plate materials are bonded together at bonding faces facing each other via a bonding portion of the sealant, and moved in parallel with the bonding faces and in opposite directions to have a relative displacement within 0.5 to 5 mm, a stress at least 0.02 N/mm 2 is applied to the bonding portion.
1. A cylindrical alkaline storage battery comprising:
an electrode group including a positive electrode, a negative electrode, and a separator;
an alkaline electrolyte;
a cylindrical battery case having: a side wall including an opening end portion; and a bottom, the battery case accommodating the electrode group and the electrolyte, and being connected to one of the positive electrode and the negative electrode;
a sealing plate for sealing the opening end portion;
an external terminal plate having a protrusion, the external terminal plate being arranged in contact with the sealing plate, and connected to the other one of the positive electrode and the negative electrode via the sealing plate;
a gasket interposed between a peripheral edge portion of the sealing plate and an inner surface of the opening end portion; and
a sealant for providing sealing between the gasket and the inner surface of the opening end portion,
the side wall having: an annular groove portion that is open at an outer surface of the side wall, the groove portion being formed along the opening end portion so as to be adjacent to the opening end portion; and a curl portion where the opening end portion is curled inward;
the curl portion, together with the side wall at a portion forming the groove portion, sandwiching the peripheral edge portion of the sealing plate to secure the sealing plate at the opening end portion of the battery case;
in at least part of the groove portion, a minimum value of a groove width L1 being within 0.2 mm;
the sealant including a polyamide resin, the sealant being formed such that when two test-plate materials are bonded together at bonding faces that face each other via a bonding portion forming of the sealant, and moved in parallel with the bonding faces and in opposite directions under a condition that a relative displacement amount is within a range of 0.5 to 5 mm, a stress at least 0.02 N/mm 2 is applied to the bonding portion.
2. The cylindrical alkaline storage battery according to claim 1 , wherein the polyamide resin has an amine value greater than or equal to 45 and less than or equal to 150.
3. The cylindrical alkaline storage battery according to claim 1 , wherein the side wall, except the portion forming the groove portion, has a thickness of 0.09 to 0.14 mm, and the side wall at the portion forming the groove portion has a projecting height in an inward direction of the battery case of 0.3 mm or more.
4. The cylindrical alkaline storage battery according to claim 1 , wherein:
the side wall has a flat portion between the curl portion and the groove portion, the flat portion having a width 1.4 to 4 times as large as a thickness of the peripheral edge portion of the sealing plate; and
a difference between an outer diameter of the flat portion and an outer diameter of a body portion of the side wall is within 0.06 mm, the body portion being a portion of the side wall other than the curl portion, the groove portion, and the flat portion.
5. The cylindrical alkaline storage battery according to claim 1 , wherein a maximum height of surface roughness (R max ) of an inner surface of the side wall in a portion from the curl portion to the groove portion is 1.2 to 6 times as large as a maximum height of surface roughness (R max ) of the inner surface of the side wall in a portion other than the portion from the curl portion to the groove portion.
6. The cylindrical alkaline storage battery according to claim 1 , further comprising a doughnut-shaped leakage preventing plate having at a center portion a hole through which the protrusion of the external terminal plate is fittingly inserted, an entire peripheral edge portion of the leakage preventing plate being in contact with the curl portion.
7. The cylindrical alkaline storage battery according to claim 6 , wherein the leakage preventing plate includes polypropylene, and has a thickness of 0.05 to 0.3 mm.