Experimental Study of Explosion Parameters of Hybrid Mixture Caused by Thermal Runaway of Lithium-ion Battery

The explosion characteristics of the runaway battery vented gas (BVG) was studied using an 8 L column type device. The effects of ambient temperature, turbulence condition, and graphite dusts-ejected along with the BVG on the explosion process-were investigated. At 25 ℃, the explosion limits of pure BVG, the maximum explosion pressure (Pmax), and the maximum rate of explosion pressure rise (dP/dt)max is 10.8% - 45.8% by volume, 0.62 MPa, and 37.6 MPa/s, respectively. At 80 ℃, the three parameters changed to 10.4%-46.5%, 0.49MPa and 35.5MPa/s. Moreover, these three parameters changed to 10.2% - 47.5%, 0.45 MPa and 33.3 MPa/s at 120 ℃. The increase in temperature reduced Pmax of BVG. While turbulence had little effect on the explosion pressure of BVG, it has significantly affected the dP/dt value. Adding graphite dusts helps BVG get to Pmax at a much lower volume concentration. As temperature increased, this effect became greater. Also, the graphite dusts can reduce the time of BVG to attain the Pmax value after igniting – the maximum reduction is from 325 ms to 158 ms. As ambient temperature increased, the combustible gas molecules were reduced, resulting in a lower Pmax value. The heat released from the BVG explosion drives the graphite involving dust explosion when oxygen is excessive. The above findings can provide a reference for the prevention of environmental explosions caused by the thermal runaway of lithium-ion batteries in process industry.