Inhibition Effect of Liquid Nitrogen on Suppression of Thermal Runaway in Large Lithium Iron Phosphate Batteries

Thermal runaway (TR) and resultant fires pose significant obstacles to the further development of lithium-ion batteries (LIBs). This study explores, experimentally, the effectiveness of liquid nitrogen (LN) in suppressing TR in 65 Ah prismatic lithium iron phosphate batteries. We analyze the impact of LN injection mode (continuous and intermittent), LN dosage, and TR development stage of LIB (based on battery temperature) at the onset of LN injection. Results reveal that intermittent LN injection demonstrates superior inhibition compared to continuous injection under identical doses. Furthermore, an increase in LN dosage enhances the inhibition effect, with absorbed heat escalating accordingly. Research shows that 6.66 kg of LN can effectively inhibit the TR of a 65 Ah lithium iron phosphate battery. Furthermore, optimal active inhibition by LN occurs before TR initiation (anomalous warming stage), allowing for the prevention of battery warming with minimal LN. This work is anticipated to offer guidance for the fire safety design of LIBs and the active prevention of TR in such batteries.