A venting valve – just the thing to prevent a lithium battery explosion
When a lithium battery overheats, it can eventually get to a thermal runaway condition where 
bad things happen. In the event of overheating the electrolyte will evaporate. At elevated temperatures, parts of the battery such as the polyvinylidene fluoride binder in the electrodes may also form gases that can eventually contribute to a bursting or exploding battery. To head off such difficulties, it can make sense to equip the lithium battery with a burst valve like this one from Hugo Benzing LLC in Wixom, Mich. It is designed to open when pressure reaches a certain point. This particular example is of a size you might find in an EV battery. The firm also makes smaller versions including some that incorporate PTFE membranes that release in the presence of high pressure, then allow gas to flow back when conditions have changed.
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The cells can be assembled into a number of series and parallel configurations resulting in a wide variety of voltage and amperage as necessary. For full details, go to the Rolled-Ribbon Battery Company website http://www.rolled-ribbon.com