A novel direct liquid cooling strategy for electric vehicles focused on pouch type battery cells

Abstract

In this work, a novel direct liquid cooling strategy for a large-scale lithium-ion pouch type cell is proposed to control the cell working temperature within the optimum range of performance and safety. With a modular design to reduce the weight impact of the fluid, the novelty of the strategy consists in directly cooling the surface of the battery cell instead of immersing the battery system in the cooling fluid. To evaluate the feasibility of the proposed strategy, a sub-system level comparison with the indirect liquid cooling strategy was developed based on the pumping power consumption criterion. Both strategies were subjected to 1C pulse tests and real driving cycles. At 1C pulse tests, the mean cell temperature was 6.4 ◦C lower, and the thermal heterogeneity decreased from 5.7 ◦C to 0.4 ◦C. The real driving cycle results showed the faster response of the direct liquid cooling strategy, which instantaneously reduced the cell temperature to the cooling setpoint after a semi-fast charge in each driving cycle. This study highlights the higher performance of the proposed strategy, which delivers more accurate thermal management without increasing power consumption. Thus, the proposed strategy provides a feasible high-performance solution for high-capacity Li-ion based electric vehicle applications.