Analysis of effectiveness of suppression of lithium ion battery fires with a clean agent

A campaign of experiments was conducted in a previously designed bench-scale wind tunnel to determine the effectiveness of suppression of lithium ion battery fires with a clean agent, Novec 1230 (CF3CF2C(O)CF(CF3)2). The experiments were performed on twelve 18650 form factor, fully charged, lithium cobalt oxide cells arranged in a rectangular array without intercell spacing. A set of baseline experiments performed at 640 l min−1 of air flow, 320 l min−1 of air flow, and 186 l min−1 of nitrogen flow indicated that, while flaming combustion had a significant impact on the speed of thermal runaway propagation through the array, fully preventing combustion did not prevent propagation. Addition of gaseous Novec 1230 to 640 l min−1 air flow immediately after the thermal runaway of the first cell produced 8.5 vol% concentration of the agent. At this concentration, which is above that recommended for suppression of traditional fires, the agent failed to suppress flaming combustion and did not prevent propagation of thermal runaway through the array. Increasing the concentration of Novec 1230 to 15.2 vol% by reducing the air flow rate to 320 l min−1 reduced the flaming combustion efficiency below 18% and prevented complete thermal runaway propagation in 67% of tests. •Suppression of lithium ion battery fires with clean agent was investigated.•Thermal runaway propagation was induced in 18650 cell arrays mounted in wind tunnel.•Effects of purge flow composition on propagation dynamics and heat release were quantified.•Addition of 8.5 vol% of Novec 1230 to air flow failed to suppress propagation.•Addition of 15.2 vol% of Novec 1230 to air prevented full propagation in 67% of tests.