Experimental Investigations on Hydrogel-Based Passive Thermal Management System for Battery Cooling

Abstract The rapid development in battery technology requires high power and high energy density applications; however, it puts significant stress on the safety and efficiency of the energy storage systems. In this regard, heat generation during charging/discharging of the battery is one of the leading factors that compromise its performance, longevity, and safety. A conventional active cooling technique is commonly employed for such applications; however, the main drawbacks are the high complexity, cost, and energy consumption. This study explores the potential of a passive cooling technique based on self-hygroscopic hydrogel for a battery thermal management system. A hygroscopic polyacrylamide-lithium chloride (PAM–LiCl) hydrogel is presented as a passive cooling material designed to regulate battery temperatures through moisture absorption and evaporative cooling mechanisms. The experimental results show that the hydrogel has an excellent water uptake capacity of up to 4.1 g of water per gram of dry hydrogel and a lower heating rate of 0.140 °C/min compared to 0.62 °C/min without hydrogel in the battery cell. Under the charge rate of 1C at 30 °C, the hydrogel reduced the surface temperature gradient and enhanced thermal uniformity. It maintained stable temperature gradients even at higher ambient temperatures, demonstrating robust thermal stability. The combination of high water retention capacity, hygroscopic salt doping (LiCl), and evaporative heat dissipation positions the PAM–LiCl hydrogel as a promising material for passive thermal management in energy storage systems.