Thermal runaway and gas venting behaviors of large-format prismatic sodium-ion battery

Abstract

Sodium-ion batteries (SIBs) have emerged as promising alternatives to lithium-ion batteries due to the advantages of low cost, abundant resources, and superior low-temperature performance. However, research on the thermal runaway (TR) behavior of large-format prismatic SIBs remains limited. To address this research gap, this work investigates the TR behavior of 185 Ah SIBs at different states of charges (SOCs). In contrast to prior research, the primary contribution of this work is the investigation of heat generation, gas production, and mechanical changes in SIBs during TR. Two significant conclusions are obtained: 1) The proportion of H₂ increases significantly with SOC, reaching as high as 42% at 100% SOC, with an explosion range of 6.5%∼69.0%, suggesting substantial combustion and explosion hazards associated with SIBs; 2) SIBs release a large amount of heat during TR, resulting in the ejection of internal hot particles as sparks. However, the intense gas production behavior during TR process effectively dissipates heat from SIBs while isolating the combustible gases from the sparks and oxygen, leading to a self-extinguishing phenomenon. This study highlights the influence of SOC on TR and gas production behavior in SIBs, providing critical insights for the advancement of electrochemical energy storage systems.