Alkaline dry battery
A leak-proof alkaline dry battery including a battery case and a seal unit for closing the opening of the battery case. The seal unit includes: a negative electrode terminal plate; a negative electrode current collector nail electrically connected to the terminal plate; and a resin seal member. The resin seal member includes: a central cylindrical part having an opening through which the body of the negative electrode current collector nail is inserted; an outer peripheral cylindrical part interposed between a peripheral edge of the negative electrode terminal plate and an open edge of the battery case; a connecting part interconnecting the central and outer peripheral cylindrical parts; and a thinned section formed in the connecting part. The body of the negative electrode current collector nail is fitted to the opening of the central cylindrical part in a particular fit relation to prevent leakage for a long time.
1. An alkaline dry battery comprising: a battery case with an opening for housing power generating elements including an alkaline electrolyte; and a seal unit for closing the opening of the battery case,
wherein the seal unit includes: a negative electrode terminal plate; a negative electrode current collector having a columnar body and electrically connected to the negative electrode terminal plate; and a resin seal member,
the resin seal member includes: a central cylindrical part having an opening through which the body of the negative electrode current collector is inserted; an outer peripheral cylindrical part interposed between a peripheral edge of the negative electrode terminal plate and an open edge of the battery case; a connecting part connecting the central cylindrical part and the outer peripheral cylindrical part; and a thinned section formed in the connecting part and configured to break due to gas pressure,
the seal unit is attached to the opening of the battery case to seal the opening of the battery case by bending the open edge of the battery case over an upper edge of the outer peripheral cylindrical part of the seal member and crimping it inward to compress the peripheral edge of the negative electrode terminal plate, and
the negative electrode current collector and the resin seal member satisfy the following formulas 1 and 2:
1.02 ≦Rc/Rb≦ 1.08 (1)
7.7≦3.14 ×Rc×L≦f ( Rc/Rb ) (2)
where Rc represents the diameter (mm) of the body of the negative electrode current collector, Rb represents the diameter (mm) of the opening of the central cylindrical part of the resin seal member, L represents the length (mm) of the opening of the central cylindrical part of the resin seal member, and
f ( Rc/Rb ): f ( Rc/Rb )=2048.4( Rc/Rb ) 2 −4473( Rc/Rb )+2456.9.
2. The alkaline dry battery in accordance with claim 1 , wherein the alkaline dry battery is of the AA or AAA size, and when the seal unit is attached to the opening of the battery case, the central cylindrical part of the resin seal member moves in the axial direction of the body of the negative electrode current collector for a distance of 0.1 to 0.4 mm.
3. The alkaline dry battery in accordance with claim 1 , wherein the alkaline dry battery is of the AA or AAA size, and the opening of the central cylindrical part of the resin seal member has a diameter of 1.05 to 1.45 mm.
4. The alkaline dry battery in accordance with claim 1 , wherein the alkaline dry battery is of the AA or AAA size, and the opening of the central cylindrical part of the resin seal member has a length of 2.2 to 3.8 mm.
5. The alkaline dry battery in accordance with claim 1 , wherein the alkaline dry battery is of the AA or AAA size, and the body of the negative electrode current collector has a diameter of 1.08 to 1.57 mm.
6. An alkaline dry battery in accordance with claim 1 , wherein the thinned section of the resin seal member does not break in an environment at 80° C. for at least 3 months, and the alkaline electrolyte does not leak between the central cylindrical part of the resin seal member and the body of the negative electrode current collector inserted through the opening of the central cylindrical part in an environment at 60° C. and a humidity of 90% for at least 3 months.