A study on effect of lithium ion battery design variables upon features of thermal-runaway using mathematical model and simulation

A thermal-runaway model of lithium-ion battery is developed by devising a resistive heating that includes short circuit current and integrating it with existing electrochemical and exothermic reaction model of lithium-ion battery. With the developed model, a guideline for designing lithium-ion battery is suggested to delay onset of thermal-runaway. First and foremost, the simulation result obtained from developed mathematical model confirms that thermal-runaway is retarded when the area of heat transfer is augmented in the cells of same volume and capacity. Next, it is also demonstrated that, under the simulation condition in which the loading level of active materials is set as a design variable, if short circuit resistance is same, thermal-runaway occurs in a lithium-ion battery with high loading level whereas thermal-runaway do not occur when the loading level is low. Assuming the same area of electrical short, thermal-runaway occurs when cathode active material of 619 [J/g] is used, but thermal-runaway does not occur with the cathode active material of 429 [J/g]. If short circuit resistance is same, a cell of which the internal resistance equals 0.025 [Ω] drives itself into thermal-runaway, while cells with higher internal resistance, i.e. 0.03 [Ω], do not.