Design and Thermal Analysis of a Passive Thermal Management System Using Composite Phase Change Material for Rectangular Power Batteries

A passive thermal management system (TMS) using composite phase change material (PCM) for large-capacity, rectangular lithium-ion batteries is designed. A battery module consisting of six Li-ion cells connected in series was investigated as a basic unit. The passive TMS for the module has three configurations according to the contact area between cells and the composite PCM, i.e., surrounding, front-contacted and side-contacted schemes. Firstly, heat generation rate of the battery cell was calculated using the Bernardi equation based on experimentally measured heat source terms (i.e. the internal resistance and the entropy coefficient). Physical and thermal properties such as density, phase change temperature, latent heat and thermal conductivity of the composite PCM were also obtained by experimental methods. Thereafter, thermal response of the battery modules with the three TMS configurations was simulated using 3D finite element analysis (FEA) modeling in ANSYS Fluent. Simulation results show that, when PCM is adequate, surrounding and front-contacted schemes are better than the side-contacted scheme in battery temperature control. While when PCM is not adequate under continuous 3C charge-discharge cycle, front-contacted and side-contacted schemes show a better performance in PCM utilization rate in the late period of melt process than the surrounding scheme due to a higher heat conduction rate from the cells to the PCMs. This paper is expected to provide useful guidelines for the design of the passive TMS in rectangular power battery applications.