Experimental study on thermal runaway of fully charged and overcharged lithium-ion batteries under adiabatic and side-heating test

Abstract In this work, the thermal runaway (TR) hazards of a 4.5 Ah 21,700 cylindrical lithium-ion battery (LIB) are investigated at 100%, 110% and 120% stage of charge (SOC). The TR behavior of the sample at elevated temperature is characterized using an extended volume accelerating rate calorimetry and a customized battery test canister. The results show that the time interval from the LIB voltage drop to the initial of TR increases with the increase of SOC. The time interval for the LIB with 120% SOC is significantly greater than 100% and 110% SOCs, which is meaningful for the early warning of TR. In adiabatic or side-heating test, the initial temperature of TR of LIBs at different SOCs is almost the same, but the temperature at voltage drop shows a downward trend as the adding SOC. The separator thermal stability of slightly overcharged LIB is lower than fully charged LIB according to the SEM and DSC tests. Besides, the TR hazards of the LIB are recommended to be determined by multiple factors, including pressure, ambient temperature and battery surface temperature.