Many portable devices such as soldier carried devices are powered by low-weight but high-capacity lithium ion (Li-ion) batteries. An effective battery thermal management (BTM) system is required to keep the batteries operating within a desirable temperature range with minimal variations, and thus to guarantee their high efﬁciency, long lifetime and great safety. In this study, a water based sodium polyacrylate (PAAS) hydrogel thermal management system is developed to handle the heat surge during the operation of Li-ion battery pack. This BTM system is tested through a series of high-intensity
discharge and abnormal heat release processes, and its performance is compared with other classical BTM systems. The test results demonstrate that the developed low-cost, space-saving, and contour-adaptable BTM system is a very economic and efﬁcient approach in handling the thermal surge of Li-ion batteries.