Performance evaluation of a hydrostatic flow immersion cooling system for high-current discharge Li-ion batteries

A Li-ion battery can experience thermal runaway when its temperature rise and temperature distribution are uneven due to fast charging/discharging and extreme hot/cold ambient temperature conditions. In Electric vehicles, a battery thermal management system is used to address these challenges and assure superior battery pack performance. The conventional methods include air and indirect liquid (cold plate) cooling thermal management systems are influencing the high thermal gradients from the top to bottom of the cell and from the cell to cell in a battery pack. Also, when the battery is being discharged at a high current rate, it is difficult to achieve the expected heat dissipation requirements. In order to solve these issues, this research article provides a hydrostatic flow single-phase dielectric immersion cooling technique for an 18,650 cylindrical cell Li-ion battery. The three-dimensional electrochemical-thermal model of an 18,650-cell submerged in dielectric fluid is designed using a Multiscale, Multi-Dimensional (MSMD) approach with the Newman, Tiedemann, Gu, and Kim (NTGK) model. The accuracy of the numerical results is validated as being within 2 degrees C with experimental data at 3C discharge rate. The experimental results are exhibited a better cooling effect with a 33 % reduction in temperature rise at 3C battery discharge rate in 25 degrees C ambient temperature. With respect to both 25 degrees C and 60 degrees C ambient temperature conditions, this cooling system has a superior cooling effect of <10 degrees C temperature rise in a cell during a high current (3C) discharge rate. The study showed that at extremely high current discharge rates and various ambient temperature circumstances, the Li-ion battery submerged in a dielectric coolant provides enhanced cooling performance and uniform temperature distribution on the battery surface compared to natural convection. This article highlighted that the immersion cooling technique is an effective cooling phenomenon during electrical abuse conditions.