EXPLOSION-PROOF SEAL PLATE FOR SEALED TYPE CELL AND PRODUCTION METHOD THEREOF

摘要

The present invention relates to an explosion-proof seal plate for a sealed cell and a production method thereof and aims at providing an explosi on- proof seal plate and production method thereof, wherein problems of a risk o f explosion of a cell due to an excessive pressure inside the cell caused by abnormal generation of a gas through a chemical reaction accompanying over charge or erroneous use of the cell or damaging of electronic equipment using the cell as the power source are solved, ignition and other accidents can be prevented with a high accuracy by reliably cutting off an electric current when the cell internal pressure increases, and the increase in the resistance due to permeation of an electrolyte can be limited. In order to accomplish this aim, the present invention provides a thin portion 7a having a breaking strength of 18-24 kg/cm2 in the central portion of an upper metallic foil 7 made of aluminum and a thin portion 8a having a breaki ng strength of 10-13 kg/cm2 in the central portion of a lower metallic foil 8 made of aluminum, wherein the diameter A of the thin portion 7a of the upper metalli c foil and the diameter B of the thin portion 8a of the lower metallic foil 8 satis fy the relation AB. The two metallic foils are welded at the central portions with an insulating gasket interposed, and encased in a metallic case 4 made of aluminum having 4 vent holes, on top of which a temperature dependent resistor 5 and a metallic cap 6 having 4 vent holes are then placed. A seal plate is obtained by sealing the periphery of the metallic case 4, with which it is possible to prevent accidents such as ignition and explosion of a cell by reliably allowing internal gas to exhaust in the event of generation of a large volume of gas under an abnormal condition of a sealed cell.