Performance Evaluation Procedures for Fire Extinguishing Agents and Devices in Small-Scale Lithium-Ion Battery Fires

Small-scale lithium-ion battery fires involve thermal runaway, propagation to adjacent cells, and possible re-ignition; therefore, flame suppression alone does not adequately reflect the extinguishing performance. This study reviewed the major test elements of KFI 630 and NTA 8133 and proposed an improved procedure based on fire and extinguishing tests using small-scale pouch-type lithium-ion batteries. In the free-burn tests, thermal runaway propagated through the five-cell test specimen within approximately 60-120 s, whereas the suppression tests showed different cell temperature histories and subsequent thermal runaway propagation behaviors depending on the extinguishing agent. The proposed revision maintains the KFI test configuration, heating method, and one-hour reignition observation period, while additionally recording the cell-by-cell thermal runaway timing, flame extinguishment time, and actual agent consumption. Additionally, a supplementary procedure is also proposed to evaluate the thermal stabilization and thermal runaway propagation delay using cell-temperature histories, cooling performance, propagation time, and the total number of cells undergoing thermal runaway. Further replication is required to establish the reproducibility and quantitative acceptance criteria for these proposed indicators.