This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooli...This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooling systems.Through a combination of numerical simulation and experimental validation,the technical advantages and mechanisms of immersion cooling are systematically explored.Simulation results indicate that under a 3C fast-charging condition(inlet temperature 20℃,flow rate 36 L/min),the immersion cooling structure 3demonstrates a triple enhancement in thermal performance compared to the cold plate structure 1:a 13.06%reduction in peak temperature,a 31.67%decrease in overall maximum temperature difference,and a 47.62%decrease in single-cell temperature deviation,while also reducing flow resistance by 33.61%.Furthermore,based on the immersion cooling model,a small battery module comprising seven cylindrical cells was designed for thermal runaway testing via nail penetration.The results show that the peak temperature of the triggered cell was limited to 437.6℃,with a controllable temperature rise gradient of only 3.35℃/s and a rapid cooling rate of 0.6℃/s.The maximum temperature rise of adjacent cells was just 64.8℃,effectively inhibiting thermal propagation.Post-test disassembly revealed that the non-triggered cells retained>99.2%of their original voltage and>99%structural integrity,confirming the module’s ability to achieve“localized failure with global stability.”展开更多
Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be exten...Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be extensively preheated prior to charge or discharge.However,conventional preheating is accomplished externally,which is slow and thus significantly increases charging times.Recently,internal heating has been demonstrated as a potential solution to quickly and uniformly preheat a lithium-ion pouch cell.However,internal heating has not been evaluated in other battery formats such as cylindrical batteries.In this work,we present a numerical model of a 4680 battery with internal heaters for fast preheating in cold environments.The effects that the number of heater layers,heating duration,resting duration,environmental temperature,and boundary heat transfer coefficient have on the temperature heterogeneity of the battery were investigated.The results show that internal heating alone reduces the temperature variation within the battery by a factor of 5 compared to external heating,and by a factor of 20 when combining internal and external heating.This study further proves that internal preheating of lithium-ion batteries is a promising thermal management strategy,and provides guidance on potential design considerations and heating protocols to implement internal heating.展开更多
文摘This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooling systems.Through a combination of numerical simulation and experimental validation,the technical advantages and mechanisms of immersion cooling are systematically explored.Simulation results indicate that under a 3C fast-charging condition(inlet temperature 20℃,flow rate 36 L/min),the immersion cooling structure 3demonstrates a triple enhancement in thermal performance compared to the cold plate structure 1:a 13.06%reduction in peak temperature,a 31.67%decrease in overall maximum temperature difference,and a 47.62%decrease in single-cell temperature deviation,while also reducing flow resistance by 33.61%.Furthermore,based on the immersion cooling model,a small battery module comprising seven cylindrical cells was designed for thermal runaway testing via nail penetration.The results show that the peak temperature of the triggered cell was limited to 437.6℃,with a controllable temperature rise gradient of only 3.35℃/s and a rapid cooling rate of 0.6℃/s.The maximum temperature rise of adjacent cells was just 64.8℃,effectively inhibiting thermal propagation.Post-test disassembly revealed that the non-triggered cells retained>99.2%of their original voltage and>99%structural integrity,confirming the module’s ability to achieve“localized failure with global stability.”
基金supported by an Early Career Faculty grant from NASA’s Space Technology Research Grants Program(No.80NSSC23K0072)the National Science Foundation Graduate Research Fellowships Program(No.2139319).
文摘Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be extensively preheated prior to charge or discharge.However,conventional preheating is accomplished externally,which is slow and thus significantly increases charging times.Recently,internal heating has been demonstrated as a potential solution to quickly and uniformly preheat a lithium-ion pouch cell.However,internal heating has not been evaluated in other battery formats such as cylindrical batteries.In this work,we present a numerical model of a 4680 battery with internal heaters for fast preheating in cold environments.The effects that the number of heater layers,heating duration,resting duration,environmental temperature,and boundary heat transfer coefficient have on the temperature heterogeneity of the battery were investigated.The results show that internal heating alone reduces the temperature variation within the battery by a factor of 5 compared to external heating,and by a factor of 20 when combining internal and external heating.This study further proves that internal preheating of lithium-ion batteries is a promising thermal management strategy,and provides guidance on potential design considerations and heating protocols to implement internal heating.
