Experimental study on the thermal management performance of immersion cooling for 18650 lithium-ion battery module

Abstract

Direct liquid cooling technology stabilizes the battery module at the ideal operating temperature by leveraging the coolant's high heat capacity and its heat dissipation ability through circulation. This study introduced a forced-flow immersion cooling method employing transformer oil as the cooling medium for 18650 lithium-ion battery modules. The performance of this cooling system design was assessed under various discharge rates, coolant flow rates, and channel positions. Experimental data reveals that the average temperature of the oil-immersion-cooled battery module was around 26.3% lower than that of the naturally air-cooled battery module under a 2C discharge condition with zero flow rate. The cooling capacity of the oil-immersion system was limited, with theoretical analyses indicating an optimal flow rate of 200mL/min. Four unique cooling channel configurations was designed: side center inlet to center outlet, side upper inlet to lower outlet, front upper inlet to lower outlet, and front center inlet to center outlet. The peak temperatures of the battery module for these setups were 31.7 ℃, 31.0 ℃, 31.0 ℃, 31.0 ℃, and 31.6 ℃, respectively, with a temperature difference of about 2 ℃. Notably, the side upper inlet to lower outlet channel configuration displays superior cooling performance. These findings contribute to advancing more efficient cooling systems and offer valuable insights for optimizing direct liquid-cooled thermal management systems for lithium-ion batteries in the future.