<p>Lithium-ion batteries used in electric vehicles generate heat due to various factors, potentially leading to fire or explosion incidents. To mitigate these risks, extensive research has focused on enhancing battery module cooling performance through thermal interface materials (TIMs). These materials, however, exhibit viscoelastic mechanical properties that change over time, affecting their thermal transfer characteristics and making it challenging to accurately predict long-term cooling performance. This study aims to quantify both the viscoelastic behavior and the thermal transfer characteristics of TIMs. By employing finite-element analysis to predict the time-dependent contact pressure of TIMs within a battery module and by calculating the corresponding thermal conductance, the cooling performance of the module can be accurately assessed. The proposed method for modeling the mechanical and thermal behavior of TIMs, while accounting for their viscoelastic nature, is expected to significantly aid in the precise design of cooling systems for lithium-ion battery modules.</p>