Heat Pipe Thermal Management Based on High-Rate Discharge and Pulse Cycle Tests for Lithium-Ion Batteries

Abstract

A battery thermal management system (BTMS) ensures that batteries operate efficiently within a suitable temperature range and maintains the temperature uniformity across the battery. A strict requirement of the BTMS is that increases in the battery discharge rate necessitate an increased battery heat dissipation. The advantages of heat pipes (HPs) include a high thermal conductivity, flexibility, and small size, which can be utilized in BTMSs. This paper experimentally examines a BTMS using HPs in combination with an aluminum plate to increase the uniformity in the surface temperature of the battery. The examined system with high discharge rates of 50, 75, and 100 A is used to determine its effects on the system temperature. The results are compared with those for HPs without fins and in ambient conditions. At a 100 A discharge current, the increase in battery temperature using the heat pipe with fins (HPWF) method is 4.8 °C lower than for natural convection, and the maximum temperature difference between the battery surfaces is 1.7 °C and 6.0 °C. The pulse circulation experiment was designed considering that the battery operates with a pulse discharge and temperature hysteresis. The depth of discharge is also considered, and the states-of-charge (SOC) values were 0.2, 0.5, and 0.8. The results of the two heat dissipation methods are compared, and the optimal heat dissipation structure is obtained by analyzing the experimental results. The results show that when the ambient temperature is 37 °C, differences in the SOC do not affect the battery temperature. In addition, the HPWF, HP, and natural convection methods reached stable temperatures of 40.8, 44.3, and the 48.1 °C, respectively the high temperature exceeded the battery operating temperature range.