An experimental study of lithium ion battery thermal management using flexible hydrogel films

• A flexible hydrogel based battery thermal management (BTM) system is developed.
• The performance of the proposed system is compared with conventional BTM systems.
• Hydrogel BTM system efficiently controls the temperature rise in discharge tests.
• The proposed system can arrest or postpone battery thermal runaway in nail tests.
• The hydrogel BTM system is of low-cost, space-saving, and contour-adaptable.

Many portable devices such as soldier carrying 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. However, the rigorous constraints imposed by the budgets in weight and volume for this specific application eliminate the possible consideration of many existing classical cooling approaches and make the development of BTM system very challenging in this field. In this paper, a flexible hydrogel-based BTM system is developed to address this challenge. The proposed BTM system is based on cost-effective sodium polyacrylate and can be arbitrarily shaped and conveniently packed to accommodate any Li-ion stacks. This BTM system is tested through a series of high-intensity discharge and abnormal heat release processes, and its performance is compared with three classical BTM systems. The test results demonstrate that the proposed 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.