Synthetic ester-based forced flow immersion cooling technique for fast discharging lithium-ion battery packs

• Published in: Journal of energy storage 2024-09, Vol.97, p.112852, Article 112852
• Main Authors: Hemavathi, S., Thiru Kumaran, A., Srinivas, Srirama, Prakash, A.S.
• Format: Article
• Language: English
• Subjects: Cell-cell temperature; Dielectric fluid; Forced flow immersion cooling; Li-ion battery pack; Maximum temperature; Synthetic ester oil
• ISSN: 2352-152X
• DOI: 10.1016/j.est.2024.112852

Rapid advancements in Li-ion battery technology are being made to meet the growing demand for efficient energy storage solutions in electric vehicles and portable electronics. However, heat generation during rapid charging and discharging remains a significant challenge, as it can lead to overheating, fire, and explosion. To address this issue, battery thermal management systems require improvements in cooling strategies. This study aims to optimize the thermal performance of Li-ion battery packs during fast discharge operation by single-phase synthetic ester oil-based forced flow immersion cooling (FFIC) technique. The study analyzes the thermal performance of the FFIC of a 4S2P LIB pack based on various flow rates, pressure drops, and pump power consumption and compares it with various conventional cooling methods and dielectric fluids. The MSMD-based NTGK battery modeling approach is used to analyze the electrical and thermal characteristics of the battery pack at 3C discharge and environmental temperature of 25 °C. The simulation findings revealed that the synthetic ester oil has a superior cooling effect than mineral oil in the 4S2P Li-ion battery pack. The experimental results showed that the synthetic ester-based FFIC Li-ion battery pack achieves an optimal pack temperature of 31.3 °C and uniform temperature distribution at the flow rate of 5 L/min and pressure drop of 228.44 Pa. Moreover, FFIC reduces temperature rise by 51 % compared with natural air convection and 35 % compared with static flow immersion cooling (SFIC) in the 4S2P lithium-ion battery pack. Also, the practical significance of the SEO-based FFIC immersion cooling technique is assessed across extreme climate zones such as −10 °C and 40 °C and determined its superior performance in Li-ion batteries. Hence, this study proved that the FFIC technique is suitable for Li-ion batteries in electric vehicle applications in terms of optimal performance, reliability, and safety during high-current discharge operations. •FFIC system for 4S2P Li-ion battery optimizes thermal performance during fast discharge.•MSMD-based NTGK battery modeling analyzes electrical and thermal characteristics at 3C discharge, 25 °C ambient.•Evaluated thermal performance with varied flow rates, pressure drops; compared to conventional cooling methods and fluids.•Optimal temperature difference (~5 °C) achieved at 5 L/min in both numerical and experimental studies.•Demonstrated effectiveness in Li-ion battery applicati