Study on Thermal Runaway of Internal Heating of Lithium Iron Phosphate Battery
The thermal runaway triggers of lithium-ion batteries mainly include needling,overcharging,heating,and locally adding heating film inside the battery to simulate the thermal runaway caused by internal short circuit of the battery.This paper explores the influence of different heating power on the thermal runaway of lithium iron phosphate battery.The pressure relief valve of four experimental batteries is not opened,all of which are caused by the failure of sealing material,leading to pressure relief and exhaust at the heating wire outlet position,which can improve the temperature resistance of sealing material.The heating power increases from 93 W to 115 W,160 W and 230 W successively,and the heating time to thermal runaway is shortened from 106 min to 70 min,42 min and 23.37 min successively.In addition,with the increase of heating power and heating rate,the triggering temperature of the battery thermal runaway can be reduced.The maximum temperature of the battery after thermal runaway is related to the heating rate and heating energy.The faster the heating rate,the smaller the additional energy added by the battery,and the lower the maximum temperature after thermal runaway of the battery.In addition,the size of the heating film is consistent,and the time required to increase the heating power and heat to thermal runaway does not show a linear relationship.The structure and morphology of the tested samples were characterized by CT.Finally,through simulation technology,the temperature variation curve of 115 W heating shell is consistent with that of 115 W internal heating shell,indicating that the thermal performance parameters of the battery are correct.
lithium iron phosphatebuilt-in heatingthermal runawaytemperature
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