Study On Burning Explosion Characteristics Of Lithium Ion Batteries In A Confined Space

This dissertation is particially supported by the National Natural Science Foundation of China“Key Technology and Experimental Verification of Water Mist Fire Suppression in Aircraft Cargo Compartment?Grant No.U1633203?”and“Low-false alarm smoke detection for civil aircraft cargo compartment based on scattering matrix analysis?Grant No.U1733126?”.Currently,the fire accidents due to lithium-ion battery thermal runaway during civil aviation transportation have occurred frequently,a self-designed experimental platform for lithium-ion battery explosion was built and experiments were carried out to reveal the effect mechanism of different intial pressures on burning explosion characteristics of lithium ion batteries in a confined space,which would provide some theoretical support for fire safety and hazard prevention of lithium-ion battery during civil aviation transportation.The typical 18650 lithium-ion battery was selected and the controlling variable method was adopted for the burning explosion experiments under the different initial pressure environments of 96kPa and 61kPa in the dissertation.This dissertation includes mainly the following two sections:?1?the influence of initial environmental pressure,heat source power,state of charge?SOC?,et al,on the burning explosion characteristics of single lithium-ion battery.?2?the influence of initial environmental pressure,heat power,SOC,battery quantities and arrangement on the burning explosion characteristics of lithium-ion battery series.For all the experiments,comparison analysis under 96kPa and 61kPa are both performed to reveal the influence mechanism of the above factors on thermal hazard,explosion pressure and smoke during and after the thermal runaway of lithium-ion batteries.The experimental results show that:?1?the burning explosion response temperature and time of lithium-ion battery decrease with the increasing heat power and SOC,as well as the temperature rise rate increases,and the temperature of the cell body increases accordingly.And the similar conclusions can be drawn for lithium-ion battery series.During the process of burning explosion,the maximum destructiveness of one battery is equal to 7.52g TNT equivalence.Thereis a greater impact on burning explosion of the lithium-ion battery under the initial pressure environment of 61kPa than under 96kPa,because the battery explosion response temperature and time increase more,and the temperature rise rate decreases larger under 61kPa.?2?There is a positive correlation between the explosion pressure and the heat power and/or state of charge for the lithium-ion battery.The explosion pressure of the single cell increases with the increase of the heat power and state of charge,the maximum explosion pressure under the initial environmental pressure of 96kPa can reach 0.228MPa,while it can reach 0.169MPa during the thermal runaway of single battery under the initial environmental pressure of 61kPa.The explosion pressure of the linear-arrangement lithium-ion battery series also increases with the increase of the heat power and state of charge,the explosion pressure of battery series under the initial environmental pressure of 61kPa is low;However,the explosion pressure trends of the battery series with different state of charge capacities are different,the explosion pressure of the 100%state of charge battery series is decreasing,and the explosion pressure of the 50%state of charge battery series first rises and then decreases.The maximum ejection pressure of surface-arrangement battery series could rise to 0.327MPa and 0.319MPa under 96kPa and 61kPa,respectively.?3?With the increase of heat source power and state of charge,the consumption of O₂and the production of CO₂ and CO increase during lithium-ion batteryexplosion.The surface-arrangement battery series has the most explosive,and its O₂ consumption and CO₂and CO production are the most.The O₂ consumption and CO₂ and CO production in the initial environment of 61kPa are more than those generated in the 96kPa environment,It means that lithium-ion batteries are more toxic in low-pressure environments.