Dodecafluoro-2-methylpentan-3-one (FK-5-1-12) is widely used in lithium-ion battery energy storage stations due to its excellent fire extinguishing performance. However, high concentrations of toxic HF (hydrogen fluoride) are generated during the fire extinguishing process. Understanding the HF generation mechanism of FK-5-1-12 and exploring methods to suppress HF are crucial for safe fire extinguishment. This study investigates the characteristics of suppressing 280 Ah lithium-iron phosphate battery fires under different ratios of FK-5-1-12, trans-1-chloro-3,3,3-trifluoropropene (R1233zd(e)), and 2-bromo-3,3,3-trifluoropropene (2-BTP). The results show that HF generation during the FK-5-1-12 fire extinguishing process occurs in two stages, with peak HF concentrations reaching as high as 1475 ppm. When FK-5-1-12 is mixed with R1233zd(e), if the mass fraction of R1233zd(e) is below 50 %, both the fire extinguishing time and HF concentration decrease as the proportion of R1233zd(e) increases. However, when the mass fraction of R1233zd(e) exceeds 50 %, the extinguishing time increases while the HF concentration decreases. Under the mass ratio of FK-5-1-12: R1233zd(e): 2-BTP being 5:5:1, the extinguishing time and peak HF concentration are 20.83 % and 3.80 % of those of FK-5-1-12, respectively. Comprehensive evaluation indicates that the ternary fire extinguishing agent has advantages such as good economic efficiency, low toxicity, and strong cooling effects. R1233zd(e) and 2-BTP are suitable as HF suppressing additives for FK-5-1-12. The research results can provide effective guidance for the safety prevention and control of lithium-ion battery fires in energy storage systems.
