Thermal abusive experimental research on the large-format lithium-ion battery using a buried dual-sensor

Abstract

The study on the thermal flow characteristics of temperature and pressure is helpful to understand the thermal runway mechanism of batteries. In this study, a 50 Ah, 3.65 V commercial prismatic battery with an Li(Ni0.6Co0.2Mn0.2)O2 cathode is tested through thermal abusive experiments. The thermal flow characteristics of thermal runaway behaviors including temperature, pressure and gas quality have studied comprehensively by the proposed method of a dual-sensor, which are buried into battery. The experimental results indicate that the thermal runaway test can be divided into five stages. The internal pressure reaches to its maximum value of 1230 kPa and the first venting of the battery is appeared during Stage Ⅲ. During Stage Ⅴ, the battery internal temperature reaches to the maximum value of 655℃, and the second venting happens. The maximum pressure appears 290s earlier than temperature in average, which can be used for warming signal. Additionally, before battery safety valve bursting, its internal pressure variation has interactions with changings in both temperature and the amount of chemical reactant. To analyze this relationship, the P-T coefficient is introduced. The P-T coefficient is positive in the temperature ranges of 30 ℃ to 65 ℃, 95℃∼ 115 ℃and 130 ℃∼ 180 ℃. This means that the internal pressure of battery increases with temperature rising, which is mainly due to the reaction gas production. In the temperature of 65 ℃∼95℃, the P-T coefficient is negative. It can be deduced that the produced reactants, such as alkanes and alkenes, are re-dissolved in the organic electrolyte solvents. In summary, this novel study will be a guidance for thermal hazards early warming and battery internal thermal state analysis, which guides the thermal safety design of batteries.