Phase change materials have been of increasing interest in thermal management of power batteries due to their high latent heat with minimum volume change. In this work, a numerical study of phase change materials is presented for the purpose of thermal control of the cylindrical power battery cells for applications in electric vehicles. Uniform heat density was applied at the battery cell surrounded by phase change material (PCM) of paraffin wax type contained in a metal housing. A two-dimensional cylindrical model was considered due to the model symmetry. The effects of power densities, heat transfer coefficients and onset melting temperatures were examined for the battery temperature evolution. Temperature plateaus can be observed from the present numerical analysis for the pure PCM cases, and the temperature level depending on the power densities, heat transfer coefficients, melting temperatures. In addition, the copper foam of high thermal conductivity was inserted into the PCM to enhance the heat transfer. The local thermal non-equilibrium between the metal foam and the PCM was taken into account in the numerical modeling. The significant thermal enhancement with copper foam was observed with lowered battery temperature.