Battery vent and method of assembly

摘要

A battery that generates a gas during charge or discharge contains a two-stage vent system including a rigid case permeable to the gas such as ethyl celluose which is permeable to hydrogen gas disposed in an expandable envelope impermeable to the gas such as metallized plastic film. The gas permeates the walls of the case and expands the envelope. The gas is vented from the envelope through a porous plug such as microporous polyethylene sealed into the film.