Quantifying Lithium-Ion Battery Hazards

Lithium-ion (Li-ion) batteries are used in a variety of applications to provide energy on demand, collectively known as Battery Energy Storage System (BESS) when assembled into racks of modules. Unfortunately, Li-ion batteries also have the potential for hazards such as fire, explosions, and the release of toxic gasses, which have the potential of amplifying hazards as BESS. Depending on the arrangement of the racks and modules, the hazards have the potential to propagate between batteries, modules, or even rack-to-rack. The consequences of the hazards are dependent upon many factors including the chemistry of the battery, the arrangement of modules and racks, and the overall geometry of the BESS equipment group or enclosure.

In this paper, the authors describe how thermal runaways can occur in BESS and evaluate potential blast impacts and resulting structural response due to release of flammable gas mixtures from BESS systems. Most current Li‐ion battery cells contain flammable electrolyte that can become a hazard if a cell is breached. In addition, Li‐ion batteries have the potential to eject flammable decomposition gases once they enter in thermal runaway where the composition of the battery gas produced by the Li‐ion batteries is typically provided by the UL 9540A test standard. Once the gas composition is determined, the combustion properties of the flammable gas mixture can be used to predict blast loads using an internal deflagration scenario (explosion confined in an enclosure) or as an open field vapor cloud explosion scenario (explosion outside an enclosure).

Finally, this paper will discuss how the blast load predictions for the BESS systems can then be utilized to develop compound blast contours for the BESS facility site for personnel injuries and/or building damage. Examples will be provided where the structural response of buildings in the vicinity of a BESS site is assessed against the predicted blast using screening methodologies (for offsite, or far-field buildings) and dynamic structural analysis methods such as Single Degree of Freedom (SDOF) analysis methodologies (for on-site or nearfield buildings). The BESS enclosures themselves can also be analyzed using SDOF as well as analyzed for debris hazard potential.