Flame-Retardant Battery Pack Case Design for Delaying Thermal Runaway: A CFD and Experimental Study

Area of Science:

• Materials Science
• Thermal Engineering
• Battery Safety

Background:

• Thermal runaway (TR) in lithium-ion batteries poses significant fire and explosion risks in electric vehicles (EVs).
• Effective thermal protection strategies are crucial for delaying or suppressing heat propagation within battery pack cases (BPCs).

Purpose of the Study:

• To propose and evaluate a novel flame-retardant BPC design for mitigating thermal runaway in EV batteries.
• To assess the design's effectiveness using computational fluid dynamics (CFD) and multiscale experimental validation.

Main Methods:

• CFD thermal analysis simulating TR with a heat source at 1107 °C and coolant flow at 17 L/min.
• Material-level tests heating flame-retardant pads to 1100 °C (±10%) for 5 min, monitoring backside temperature (<160 °C).
• Full-scale BPC tests with upper case heating >500 °C for 10 min (backside temperature <150 °C) and module-level TR experiments.

Main Results:

• Material tests showed backside temperatures below 160 °C when pads reached 1100 °C.
• Full-scale BPC tests maintained backside temperatures below 150 °C under extreme heating.
• Module-level tests demonstrated a reduction in external temperature from 240-260 °C to below 150 °C with the flame-retardant layer.

Conclusions:

• The proposed flame-retardant BPC design effectively delays thermal penetration during simulated thermal runaway events.
• The design maintains external safety temperatures, crucial for preventing catastrophic failures in EV battery systems.
• This study provides practical guidelines for developing safer EV battery pack solutions.