Multimodal synchronous monitoring platform for state of charge stratified thermal runaway in lithium iron phosphate batteries

Abstract

As a critical component in electric vehicles and energy storage systems, the dynamic relationship between state of charge (SOC) and thermal runaway (TR) propagation in LiFePO₄ batteries remains insufficiently understood. To address the critical limitation of existing TR testing methods in achieving synchronized multiparameter acquisition, this study developed an integrated multi-physics monitoring platform enabling spatiotemporal correlation analysis across the entire TR chain-from triggered initiation, heat/smoke release, gas speciation, 2 dimension temperature field reconstruction (infrared thermography), to TR process visualization. Systematic investigation of 18650-type LiFePO₄ cells across SOC gradients revealed distinct failure modes: 100% SOC cells exhibited predominant heat-driven failure with total heat release reaching 5.95 MJ/m² (a 5-fold increase versus 50% SOC cells), while 50% SOC cells demonstrated prioritized smoke aerosol release (520% higher particulate density than 100% SOC) with delayed combustible gas generation. This platform overcomes single-parameter detection constraints in conventional methods, providing multiscale experimental evidence to guide SOC-stratified safety protocols and phase-change thermal barrier material optimization for lithium-ion battery systems.