A Comprehensive Comparison of the Phase Change Material-Based Internal and External Cooling Systems

Abstract

Being employed in a wide range of energy storage applications, such as solar energy storage systems and electric vehicles (EVs), lithium-ion batteries (LIBs) have become an important link in the chain of clean energy harvest and delivery and have played a crucial role in low-carbon energy transitions. Thermal management is critical for maintaining the efficiency, safety, and longevity of LIBs due to the exothermic behavior and high temperature sensitivity of LIBs. A desirable thermal management system should be able to help sustain a desired operating temperature range and a small temperature gradient within batteries.The heat accumulation effect in the center of cylindrical LIBs has been observed and experimentally studied by Shah et al. [1] and Zhang et al. [2]. The insufficient cooling at the battery center can cause temperature nonuniformity and lead to performance degradation of batteries in long-term operation. We have previously reported a phase change material (PCM)-based internal cooling system for alleviating the heat accumulation in 18650-type LIBs [3, 4]. In this presentation, the internal cooling system will be thoroughly compared with an external PCM-based cooling system in terms of their weight and volume added to the entire battery systems, their cooling effectiveness for single batteries of different sizes and radial thermal conductivities, and the necessity of increasing the thermal conductivity of PCM through adding additives.