Persistent gas hazards partitioned from post-thermal runaway lithium-ion battery residue

Improvements in lithium-ion battery (LIB) safety rely on understanding the thermal runaway failure of the cells. Thermal abuse tests are done on LIBs to study their exothermic reaction kinetics and gaseous hazards. Typically, testing is conducted in either pressure vessels or accelerating rate calorimetry (ARC) systems. These experimental systems are often used with little cleaning between tests, raising questions about whether the accumulated or adhered vented products pose respiratory and other health concerns. Also, the guidelines on personal protective equipment (PPE) for researchers often do not specifically address hazards associated with LIB thermal abuse tests. There is a relative lack of data on what species might be re-emitted from these experimental systems and how standard PPE reduces exposure to any off-gassed species. To help answer some of these questions, this paper characterized gas emissions from a vessel containing LIB residue post-thermal runaway, detecting species including electrolyte solvents, dimethylcyclosiloxanes, and other low-volatility organic compounds. The most abundant species were ethylene carbonate (39 ppb) and propylene carbonate (34 ppb). None of the species concentrations from this well-ventilated vessel posed acute toxicity, but repeated exposure may result in chronic health impacts. Fabric samples from clothes exposed to the vessel headspace re-emit the adsorbed gases, which extends the duration of inhalation exposure for individuals. The low volatility of the species was further supported by partition coefficient values above one, indicating their persistence and dermal exposure risks. Respirator effectiveness against gases evolved from LIB residue was investigated. Suggestions on improving worker safety were given based on the results of this paper.