A device for preventing thermal run-away in a battery. The device includes a main compartment that is divided into a plurality of sub-compartments. A layer of material separates (i) a first sub-compartment containing a first chemical from (ii) a second sub-compartment containing a second chemical. In the event that a thermal run-away event is either detected or predicted, the layer of material degrades/is degraded and allows the chemicals to mix. The chemicals form an endothermic process that cools the battery preventing, or at least delaying, the thermal run-away event.