Lithium-ion battery thermal management using heat pipe and phase change material during discharge-charge cycle: A comprehensive numerical study

Thermal management of lithium ion battery has become a critical issue in recent years. In this study, a thermal management module with a sandwich structure consisting of a battery, phase change material, and heat pipe is assembled. The battery temperature response is experimentally investigated for battery, heat pipe and phase change material composite with three discharge and charge cycles. A lumped thermal model is built to consider the coupling of battery heat generation, phase change material melting, and transient thermal response of heat pipe. The underlying coupling mechanism of battery temperature and phase change process is revealed at different environmental temperatures, heat transfer coefficients at condensation section, and thickness ratios of phase change material and battery. The model is validated with the experimental data in one discharge/charge cycle. A continuous safe cycling is difficult to maintain for battery with the air convection and only phase change material. The utilization of heat pipe can recover the latent heat of phase change material with an appropriate melting point at the end of each cycle to ensure a low battery temperature for long-time cycling. Four stages, namely, sensible heat, latent heat, solidification, and steady stage, are found in each cycle for the proposed cooling module. Then, the coupling mechanism of battery heat generation and heat transfer in heat pipe and phase change material is identified. The condensation section for heat pipe may operate at the unsustainable, sustainable, and uneconomic regions. To guarantee safe battery temperature, low energy consumption, and sufficient module energy density in long-time cycling simultaneously, the phase change material melting point is recommend to be at least 3 degrees C higher than environmental temperature, and the heat transfer coefficient in the condenser is recommended to range from 30 W/m(2).K to 60 W/m(2).K with an optimum thickness ratio of 0.17 associated with a phase change ratio of approximately 0.55.