A hybrid cooling method with low energy consumption for lithium-ion battery under extreme conditions

Hybrid battery thermal management system (BTMS) has received more and more attention because of its high efficiency. However, many factors significantly affect the energy consumption and performance of hybrid BTMS, so it is urgent to propose a reasonable cooling method and a multi-objective optimization method with low computational load. In this work, a hybrid cooling method combing passive cooling and active cooling is pro-posed, and the effects of pump start-up time, inlet temperature and flow rate on the thermal and electrical performance of the battery module are studied by conceptual experiment. Thermal-electrical performance co-efficient (TEP) and energy utilization efficiency coefficient (EUE), two dimensionless numbers derived from prior information about the objective parameters, are proposed to evaluate and optimize the active cooling strategy. The experimental results show that the passive cooling strategy can meet the heat dissipation requirements of the battery module in low rate conditions, and even in high-temperature environments. The liquid cooling strategy needs to be adopted only under extreme condition (3C discharging at 35 degrees C), and starting the pump prematurely not only causes greater energy consumption, but also reduces TEP due to uneven heat dissipation. According to the deterioration mechanism of temperature difference (Delta T), it is considered that the best time to start the pump is when the maximum temperature (T-max) of the battery module reaches the upper limit of the phase transition temperature. Based on this view, the optimized cooling strategy only uses 6.51% of energy consumption to control the temperature characteristics of the battery module within the safe range, and ensure that the discharge capacity is higher than 98.5%.

Automated summary

This study proposes a hybrid cooling method for hybrid battery thermal management system (BTMS) and investigates the effects of pump start-up time, inlet temperature, and flow rate on the thermal and electrical performance of the battery module through experimental research. The results show that passive cooling strategy can meet the heat dissipation requirements in low-rate conditions, while liquid cooling strategy is only required under extreme conditions. The optimal pump start-up time is when the maximum temperature of the battery module reaches the upper limit of the phase transition temperature.