Explosion venting studies of constructure in lithium-ion battery environments

Lithium-ion battery thermal runaway (LIBTR) poses a serious explosion hazard in enclosed spaces such as warehouses, charging rooms, and energy storage facilities. Despite the increasing attention and regulation of explosion venting in battery storage systems, the current standards lack specific guidance for calculating venting areas in LIBTR environments. To address this issue, an experimental study was conducted in this study using an 8-liter cylindrical explosion tank equipped with five different diameters (10.5, 15, 21.2, 30 and 60 mm) and venting devices with adjustable static opening pressures. The gas released by the thermal runaway of ternary lithium-ion batteries was used as the experimental material. CO, H₂, CH₄, C₂H₄, and CO₂ were pre-mixed in actual proportions and used as a combustible mixture. At the same time, graphite dust with a D50 of 4 μm and a carbon purity of 99% was added to the hybrid explosion test to determine the effect of anode graphite dust on the explosion venting characteristics of lithium-ion batteries. High-energy ignition was used to simulate the worst-case scenario, igniting pure BVG (battery vent gas) and BVG-graphite dust mixtures under turbulent conditions. The pressure sensor monitored the real-time overpressure and recorded the maximum explosion relief pressure (p_red) as the critical output. The results showed that the p_red produced by pure BVG was always higher than that of the mixture containing graphite, indicating that graphite particles have a mitigating effect on the severity of the explosion, which may be due to heat absorption. Therefore, the influence of solid particles ejected by thermal runaway can be ignored when designing the explosion relief. p_red decays exponentially with the increase of the explosion relief diameter and grows logarithmically with the opening pressure p_stat of the explosion relief device. Based on the experimental data and combined with the specification GB50016, the calculation formula for the explosion relief area of lithium-ion battery structures was obtained, and the commonly used pressure relief ratio C is given as 0.11.