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

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.