Thermal runaway
In one line
Self-sustaining exothermic chain reaction in a lithium-ion cell that can propagate to fire or explosion.
What it means
Thermal runaway occurs when a lithium-ion cell's internal temperature exceeds the threshold for electrolyte decomposition (~150°C), releasing more heat and accelerating reactions until the cell ruptures. Propagation to neighbouring cells is the primary BESS fire concern. LFP chemistry has a much higher runaway threshold (~270°C) and lower energy release than NMC — one reason LFP dominated utility-scale BESS by 2026. NFPA 855 and UL 9540A standards govern containment.
Related terms
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