Safety Evaluation of a Sodium-Ion Cell: Assessment of Vent Gas Emissions under Thermal Runaway

Na-ion batteries are presented as a complementary technology to Li-ion batteries, that comply with the performance requirements of various applications without being submitted to the critical raw material dependencies pertaining to Li-ion batteries. Several major industrial actors are now committed to produce these batteries, advocating among others the safety gain of such technology. Available data on their behavior under thermal runaway are nonetheless very limited. This experimental work brings new elements of vent gas characteristics of Na-ion (Na3V2(PO4)2F3, NVPF) cells when thermally abused. A detailed gas analysis was performed in order to determine both composition of the gas mixture and related emitted volume. In our test configuration, no flames were observed, and the fumes were mainly composed of electrolyte compounds (organic carbonates). A simple comparison with Li-ion technology showed similarities with LiFePO4 (LFP) chemistries in terms of the nature and quantity of emitted gas.