Multi-directional synergistic effects of air-cooling and liquid-cooling on the thermal runaway propagation of lithium-ion batteries

Thermal runaway (TR) in lithium-ion batteries (LIBs) remains a critical bottleneck hindering their widespread adoption. Investigating and mitigating TR propagation (TRP) is essential for ensuring the safety of electric vehicles (EVs) and energy storage systems (EESs). This study conducted a numerical investigation on the synergistic effects of combined air–liquid cooling systems. A three-dimensional TRP model was established to systematically analyze the impact of standalone air-cooling, standalone liquid-cooling, and the coupled interaction of both cooling methods on TRP under different flow direction configurations. Simulation results indicate that air-cooling exhibits a superior inhibitory effect on batteries in a thermal runaway state, while liquid-cooling demonstrates better performance in inhibiting the propagation of thermal runaway. Additionally, the influences of the flow direction configurations for air–liquid cooling are relatively small. Although the overall cooling effect of air–liquid co-cooling is better than that of a single cooling method, the incremental temperature reduction from co-cooling is smaller than the simple superposition of individual air-cooling and liquid-cooling effects. Notably, compared with air-cooling, liquid-cooling shows a stronger capability in suppressing TRP. These findings provide an important theoretical basis for optimizing cooling system design and balancing heat dissipation efficiency with safety.