Thermal runaway and flame propagation of lithium-ion battery in confined spaces: Experiments and simulations

The thermal safety of lithium-ion batteries (LIBs) in confined spaces remains a critical challenge in power battery pack design. This study conducts a multidimensional evaluation into the effects of spatial scales on thermal runaway (TR) characteristics through integrated experimental and simulation approaches. Key findings reveal that reducing spatial volume from 8.0 x 108 mm3 to 2.88 x 105 mm3 significantly advances the TR trigger time of single cells by 973 s (from 1490s to 517 s), attributed to accelerated heat accumulation under degraded thermal dissipation. Furthermore, the TR propagation interval between adjacent batteries shortens by 64 s, revealing that spatial compression accelerates the chain reaction of TR through enhanced heat transfer. The simulation based on the Fire Dynamics Simulator (FDS) demonstrated the flame development dynamics in a confined environment, with a heat release rate simulation error within 4 %. Notably, vertical height reduction proves pivotal in flame suppression-spaces below 80 mm reduce heat flux to adjacent batteries by 52.3 % compared to 800 mm. These findings establish key spatial scale threshold parameters for thermal safety strategies in transportation and storage scenarios. And the innovative application of FDS provides advanced engineering solutions for battery pack design and TR fire prediction.