پيمان ايراني

Lithium-ion batteries are widely used as the main energy source for electric vehicles due to their high energy density an‎d power. Excessive temperature rise in batteries causes a phenomenon called thermal runaway, which is caused by exothermic chain reactions in the battery. These reactions cause a sharp increase in the temperature inside the battery, which causes instability an‎d destruction of the internal structure of the battery, an‎d ultimately leads to battery failure. Therefore, accurate modeling of this phenomenon an‎d estimation of its occurrence time are of great importance in battery research. Also, providing an appropriate solution to prevent the destructive phenomenon of thermal runaway is necessary an‎d essential to ensure optimal battery performance. In this thesis, first, the thermal runaway phenomenon in the 18650 lithium-ion battery is modeled using COMSOL software, an‎d the occurrence time of this phenomenon is obtained for different charging states (2 C to 5 C). by developing a thermal management system based on phase change materials, the effect of the thickness of the phase change material on delaying the occurrence of thermal runaway in different battery charging states has been calculated. The results show that the amount of time it takes for thermal runaway to occur in a battery with an electric current of 60 A/m2 with a charge an‎d discharge time of 360 seconds (charge/discharge rate: 5 C) is 2860 seconds without cooling, but 8250 seconds with 5 mm of phase change material. Also, the amount of time it takes for thermal runaway to occur in a battery with an electric current of 36 A/m2 with a charge an‎d discharge time of 600 seconds (charge/discharge rate: 3 C), is 6745 seconds without cooling, but 19481 seconds with 5 mm of phase change material. The amount of time it takes for thermal runaway to occur in a battery with an electric current of 24 A/m2 an‎d a charge an‎d discharge time of 900 seconds (charge/discharge rate: 2 C) is 13734 seconds. Also, from a study of a battery with an electric current of 60 A/m2 an‎d a charge an‎d discharge time of 360 seconds (charge/discharge rate: 5 C) in a state without cooling, it was seen that up to a temperature of 383 K, the only source of electrochemical heat has an effect on increasing the battery temperature, an‎d before this temperature, the heat from exothermic chemical reactions can be ignored but from a temperature of 383 K onwards, the heat from exothermic chemical reactions can no longer be ignored, an‎d above a temperature of 482 K, the electrochemical heat source can be ignored in comparison to the heat from exothermic chemical reactions.

پديده فرار حرارتي , ماده تغيير فاز دهنده , مديريت حرارتي باتري , باتري ليتيوم-يون

Thermal runaway phenomenon , Phase change material , Battery thermal management , Lithium-ion battery

Peyman Irani

Dr Ayat Gharehghani