Study on inhibitory efficacy of dry ice as a novel fire extinguishing agent for lithium-ion batteries

• Addresses key limitations (insufficient cooling, re-ignition, toxic gases) of conventional agents in LIB fire suppression, systematically applying dry ice to suppress TR and TRP. • Has practical value for enhancing safety of energy storage systems. • Systematically verifies dry ice’s suppression efficacy on 26700 cylindrical LIBs by varying injection quantity and timing. • Investigates dry ice’s efficacy on 50 Ah prismatic batteries, achieving rapid fire extinction and temperature reduction. • Proposes a multi-physical field synergistic suppression mechanism of dry ice: “gas-driven accelerated phase transition – low-temperature gas cloud rapid fire extinction – thermal resistance barrier sustained cooling”. Conventional fire-extinguishing agents face significant challenges—including insufficient cooling capacity, re-ignition risks, and toxic gas emissions—when suppressing lithium-ion battery (LIB) fires, representing a critical bottleneck restricting the development of fields such as energy and Combustorage. To address this, we propose and validate dry ice as a highly efficient LIB fire suppressant. First, a study on dry ice’s efficacy in inhibiting thermal runaway propagation (TRP) in 4000 mAh cylindrical LIBs demonstrates optimal suppression during early-stage fire development, with efficacy positively correlated with discharge quantity. Further validation on a 50 Ah energy storage cell confirms that dry ice extinguishes open flames within 3 seconds while significantly reducing surface temperature, effectively halting TR progression. Finally, the fire-extinguishing mechanism of dry ice was summarized, i.e., gas-driven accelerated phase transition - rapid fire extinction by low-temperature gas cloud - sustained cooling via thermal resistance barrier. This multi-phase mechanism rapidly blocks TR propagation chains. Collectively, this work provides an efficient and feasible fire-suppression strategy to mitigate the major process safety risk posed by LIB thermal runaway (TR).