This article reports a recent study on a liquid cooling-based battery thermal management system (BTMS) with a composite phase change material (CPCM). Both copper foam and expanded graphite were considered as the structural materials for the CPCM. The thermal behaviour of a lithium-ion battery was experimental investigated first under different charge/discharge rates. A two-dimensional model was then developed to examine the performance of the BTMS. For the copper foam-based CPCM modelling, an enthalpy-porosity approach was applied. The numerical modelling aimed to study the impacts of CPCM types and inlet velocity of heat transfer fluid on both the maximum battery temperature and temperature distribution under different current rates. Dimensional analyses of the results were performed, leading to the establishment of relationships of the Nusselt numbers and dimensionless temperature against the Fourier and Stefan numbers.