Heat generation and thermal runaway of lithium-ion battery induced by slight overcharging cycling

Slight overcharging cycling occurs due to the malfunction of charge control, inconsistency of lithium-ion batteries and inappropriate battery management. It is important to find whether it causes heat accumulate, increases the temperature of battery and triggers thermal runaway. The results of thermal stability test of slightly overcharged batteries indicate that the thermal stability of slightly overcharged battery decreases due to the cathode structure change when the voltage is less than 4.6 V. When it is greater than 4.6 V, lithium plating also makes battery thermal stability decrease. The results of heat generation and thermal runaway tests of batteries with and without current interruption device indicate that the internal resistance increase after slight overcharging is why the heat generation of battery increases. The heat generation induced by side reaction increases when the temperature reaches the threshold. The temperature threshold of exothermic reactions decreases during charging compared to that during rest with the same state of charge (SOC). Although the cycling is interrupted, thermal runaway still occurs. The battery with lower temperature and higher SOC is more dangerous than that with higher temperature and lower SOC in some cases. It is important to control SOC and temperature during charging.