A novel pulse resistance based thermal runaway early detection approach for lithium-ion and sodium-ion batteries

Temperature monitoring of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) is essential for safe operation, as excessive temperature can trigger a thermal runaway (TR) event. Although surface temperature sensors have traditionally been used, their limitations have led to the exploration of alternative methods. Notably, estimating temperature based on pulse resistance (RDC) has emerged as a promising approach. Nonetheless, this method has not yet been investigated at temperatures exceeding the cell's safety limits, highlighting a research gap for its application in TR early detection. In this study, the RDC-temperature relationship was characterized at temperatures exceeding the cell's safety limits for two different LIB technologies and a SIB. The results revealed a turning point in the RDC-temperature relationship between 60 degrees C and 70 degrees C for both LIB technologies and at approximately 110 degrees C for the SIB. From this turning point, RDC increases with increasing temperature. This contradicts the loss of sensitivity of RDC to temperature variations predicted by the Arrhenius model at temperatures typically encountered during a TR event. Finally, a novel TR early detection approach based on the characterized RDC behavior during a TR event is proposed. The strength of the method lies in the combination of two monitored RDC properties changing during TR.