Impact of state-of-charge and temperature on the cross-plane thermal conductivity of a Li-ion pouch cell

Abstract

A thorough understanding of the thermal transport characteristics of Li-ion batteries is critical for the development of accurate thermal models and the enhancement of thermal management strategies. In this study, the cross-plane thermal conductivity (k⊥) of a commercial 20 Ah Li-ion pouch cell was systematically measured across a broad range of state-of-charge (SOC) levels and temperatures (20.6 to 43.3∘C) using a custom-designed guarded hot plate apparatus. The results indicate that at room temperature (27.3∘C), k⊥ decreases with increasing SOC, reaching a minimum near SOC=80%, followed by a marked increase at SOC=100%. Furthermore, at SOC=100\%, k⊥ increased by approximately 0.188 Wm-1K-1 (80% enhancement) as the temperature rose from 20.6 to 43.3∘C. The observation shows that k⊥ consistently increases with temperature across all SOC levels, exhibiting nearly consistent slopes. To elucidate these trends, various contributing factors were systematically examined.