Explosion protection for prompt and delayed deflagrations in containerized lithium-ion battery energy storage systems

Explosion hazards can develop when gases evolved during lithium-ion battery energy system thermal runaways accumulate within the confined space of an energy storage system installation. Tests were conducted at the cell, module, unit, and installation scale to characterize these hazards. Three installation level tests show that explosion scenarios can occur as prompt ignitions within seconds of cell gas venting or delayed ignitions where gases ignite after a longer duration of accumulation, especially when fire protection systems are actuated. Deflagration venting and exhaust ventilation system design approaches that can be implemented at the installation level are evaluated using a dataset generated from cell, module, and unit level tests. Data from the installation level tests demonstrate the use and effectiveness of deflagration venting for containerized li-ion battery energy storage systems. • Propagating thermal runaways can create prompt and delayed explosion hazards by producing readily ignitable gaseous environments. • Prompt deflagrations can be mitigated using NFPA 68 deflagration vent designs. • Delayed deflagrations can be mitigated using NFPA 69 mechanical exhaust system designs. • Thermal runaway gas production, flammability, and explosibility data can be used as inputs for NFPA 68 and NFPA 69 calculations.