To provide an explosion-proof non aqueous electrolyte secondary battery having a current-carrying cutout gear that safely and surely shuts off an electrical connection inside a battery, when an excessive change has occurred as well as that a battery which does not operate at normal usage or while being stored at a high temperature.
A breaking pressure setting method of an explosion-proof non aqueous electrolyte secondary battery is provided with a pair of an upper and a lower valve plates 1, 2 electrically and mechanically connected each other at a sealed part and is structured, so that a current carrying is cut off by breaking the mechanical connection between a pair of the upper and lower valve plates 1, 2 wen an inner pressure of a battery case 7 is larger than a specified value. A breaking pressure, when the mechanical connection between a pair of the upper and lower valve plates 1, 2 is broken, is set so as to decrease in accordance with the increase in space volume occupying ratio inside the battery.
MORI KATSUHIKO
MASUMOTO KANEHITO
TSURUTA KUNIO
