Research on Variation Rules of Characteristic Parameters and Early Warning Method of Thermal Runaway of Lithium Titanate Battery

Aiming at prominent problems such as thermal runaway triggered by heating, thermal runaway triggered by overcharge and thermal runaway triggered by nail penetration of lithium titanate battery, the paper studied the variation rules of characteristic parameters such as battery surface temperature, environment temperature, battery voltage, characteristic gas and electrolyte vapor and studied the early warning method of thermal runaway of lithium titanate battery. The results showed that both overcharging and heating could trigger thermal runaway of lithium titanate battery, and there was less chance of thermal runaway triggered by nail penetration; a large amount of electrolyte vapor and smoke would be generated in the early stage of thermal runaway; the characteristic parameters of thermal runaway changed dramatically. In the enclosed space, the reference values of the thermal runaway characteristic parameters of lithium titanate battery change like this: The battery surface temperature or the environment temperature can reach 180 ℃, or the average heating rate can reach 5 ℃/s and above and last for 3 s; the battery voltage drops to 0 V in a short time, and the peak rate of decline can reach 0.4 V/s and above; the concentration of H2 can reach 100 ppm, the increase rate of H2 concentration can reach 5 ppm/s and above, and can last for 3 s and above; VOC gas concentration can reach 10000 ppm, and its concentration increase rate attains 1000 ppm/s and above, and can last for 3 s and above.