Research On Thermal Runaway Disaster Control Method Of Lithium Ion Battery Module

Lithium-ion batteries are widely used because of their high energy density,long service life and no environmental pollution.Due to the limited energy storage of a single cell,multi-cell battery modules are composed of series or parallel connection to meet the demand of high energy.However,when one or more batteries in the cell module lose thermal control,it will affect the surrounding cells,and even cause thermal loss of control of the cell module.In this paper,the thermal runaway and spread law of lithium-ion battery under overcharge and abuse conditions were studied.First of all,the thermal out-of-control mechanism of lithium-ion battery is analyzed in detail,and the experimental system was designed and built for the study of thermal runaway spread law of lithium-ion battery module.,relying on this system,the spread law of thermal runaway caused by thermal runaway of the master battery was explored experimentally.On this basis,the method of restraining thermal runaway spread of battery pack was studied,which provided reference for structural design and thermal runaway control of battery module It can provide the basis for the control and blocking technology.The main findings and conclusions of the study are as follows:(1)The experimental system of thermal runaway propagation law of lithium-ion battery module is designed and built,and the feasibility of the system is verified by experiments.(2)The effects of the relative number of the master battery and the delivered battery,the state of charge of the delivered battery and the distance between the master battery and the delivered battery on the thermal runaway propagation of the delivered battery were studied in the thermal insulation environment.The results show that: increasing the relative number of the master battery and the delivered battery or the state of charge of the delivered battery can promote the occurrence of thermal runaway spread of the battery,and increasing the distance between the master battery and the delivered battery can weaken the heat transfer intensity of the master battery to the delivered battery,and hinder the thermal runaway spread of the lithium-ion battery.When the distance is sufficient,the runaway spread of the delivered battery can be avoided.Therefore,it can be concluded that the delivered battery must first contain enough electricity,and can obtain enough heat and heat flux when the main generator battery is out of control.(3)By installing the aerogel insulation sheet and the aerogel insulation sheet between the master battery and the delivered battery,the two heat insulation modes of the battery are wrapped,thereby enhancing the thermal resistance between the master battery and the delivered battery.The results show that: when there is thermal resistance between the master battery and the delivered battery,it can effectively block the thermal runaway spread of the master battery,in which the heat insulation method of wrapping the master battery weakens the heat dissipation efficiency of the battery,and the heat is easy to accumulate,which may still cause the thermal runaway spread of the delivered battery.Therefore,loading the independent heat insulation sheet is a more effective way to block the thermal runaway spread of the battery module Law.(4)Using water,water film foam extinguishing agent and Perfluorocarbons extinguishing agent to control the thermal runaway of a single grain overheated main runaway battery and a heat runaway battery module respectively.The experimental results show that the three kinds of fire extinguishing agents can effectively reduce the temperature rising rate of the battery,and successfully inhibit the thermal runaway spread of the battery,among which Perfluorocarbons fire extinguishing agent has the best effect.In addition,before the thermal runaway of the battery,if the environment in the battery box contains enough fire extinguishing agent,the thermal runaway spread of the battery pack is expected to be avoided.