Abstract: Take Lithium iron phosphate energy storage battery as the experimental object, the fire extinguishing effect of heptafluoropropane on lithium iron phosphate battery was studied under the space condition of free expansion and limited expansion by splint. The change of temperature and voltage in the fire-extinguishing process of heptafluoropropane on lithium iron phosphate energy storage battery fire were studied and the fire-extinguishing effect of it was analyzed. The results showed that for free-expanding battery fires, heptafluoropropane can stop its thermal runaway reactioneffectively. For the battery with limited expansion, the thermal runaway process of the battery itself is more intense, and the temperature keeps rising for a longer time after extinguishing the fire. The second thermal runaway or even reburns of the battery happens. In practical application, safety and cost should be taken into consideration comprehensively to set up appropriate expansion space for the battery, and the fire-extinguishing agent of heptafluoropropane should be released as soon as possible.

Key words:  heptafluoropropane, lithium iron phosphate energy storage battery, expansion space, combustion stage, fire extinguishing effect