The Study Of Thermal Runaway Inhibition Of Lithium-ion Battery By Liquid Immersion Method

With the technological development of battery and the requirement of energy around the world,lithium-ion battery has been widely used in many area such as electric vehicles,cell phones or consumer electronic products.However accidents caused by thermal runaway of lithium-ion batteries occur from time to time,which can result in catastrophic damages on the people`s property and life.Therefore the research on the suppression technology of hazards for lithium-ion battery when the thermal runaway was occurred is very necessary.In order to reduce the hazard caused by thermal runaway of lithium-ion battery,it is necessary to restrain thermal runaway of lithium-ion battery timely.Three type of lithium-ion batteries were selected as the samples in this research,which is ternary lithium battery,cobalt acid lithium batteries and lithium iron phosphate battery.The experiments of lithium batteries with different SOC(state of charge,SOC)was carried out under liquid immersion.Analysis of characteristic parameters of thermal runaway of lithium battery.Effectiveness of liquid immersion on restraining thermal runaway of lithium-ion battery was discussed.The liquid used in the experiment need to have the characteries such as flame retardant,insulation and good thermal conductivity etc.to accommodate actual demand.Transformer oil and water-glycol flame retardant hydraulic oil has been selected in this article.Experimental data has been analysed comprehensively.The conclusions are summarized as follow:(1)Thermal runaway temperature of lithium-ion battery part which direct contact with immerse liquid is significantly lower than the thermal runaway temperature of lithium-ion battery in atmosphere.Temperature of ternary lithium battery reduced 522.4℃ at most,temperature of cobalt acid lithium batteries reduced 356 ℃ at most,temperature of lithium iron phosphate battery reduced 223.1 ℃ at most;(2)The amount of CO produced by 50% SOC and 25% SOC ternary lithium batteries during thermal runaway under the condition of flame retardant hydraulic oil immersion is less than that under the condition of transformer oil immersion,and the differentials are 139.4 ppm and 157.4 ppm,respectively;(3)The CO production of cobalt acid lithium batteries during thermal runaway under transformer oil immersion is less than that under flame retardant hydraulic oil immersion.The differentials of CO production during thermal runaway of 75% SOC,50% SOC and 25% SOC cobalt acid lithium batteries under the two different liquid immersion conditions are 13 ppm,12.75 ppm and 1 ppm,respectively;(4)The CO generated by the thermal runaway of lithium iron phosphate battery under the condition of flame retardant hydraulic oil immersion is less than that under the condition of transformer oil immersion.The differentials of CO production during thermal runaway of 75% SOC,50% SOC and 25% SOC lithium iron phosphate batteries under the two different liquid immersion conditions are 18.45 ppm,2.3 ppm and 2.92 ppm,respectively;(5)The mass loss of lithium-ion battery after thermal runaway experiment in transformer oil immersion is less than lithium-ion battery after thermal runaway in flame retardant hydraulic oil immersion.The maximum differentials of mass loss of ternary lithium battery,cobalt acid lithium batteries and lithium iron phosphate battery after thermal runaway in transformer oil and flame retardant hydraulic oil is 2 g,1 g and 3 g,respectively.Overall,thermal runaway disasters and toxic flammable gas generation of lithium-ion battery thermal runaway can be inhibited by liquid immersion method and avoid the secondary disasters from happening.