Experimental Study On Thermal Runaway Propagation Of Lithium Ion Battery At Different Distance

With the energy density of lithium ion batteries increasing gradually,safety issues become increasingly severe.The propagation of thermal runaway may cause a“domino”effect,with serious consequences.So research on the propagation process has become a hot topic of current research.In order to improve the overheat safety,thermal runaway propagation experiments on 18650-26 JM ternary lithium-ion battery has been considered with a state of charge?SOC?of 0%,50%and 100%in this paper.The influence of different vertical and horizontal distances between batteries on the experimental process,batteries surface temperature,safety valve cracker and ejection time,mass loss,CO and SO₂ concentration,heat release rate?HRR?and heat released are studied.THS1 batch batteries for vertical distance and TIT3 batch batteries for horizontal distance are compared.The main conclusions are as follows:Whether it is the experiment of vertical distance or the experiment of horizontal distance,the occurrence of thermal runaway greatly promotes the occurrence of thermal runaway propagation.Firstly,experiment with different vertical distances between the upper and lower batteries are carried out.For the upper battery,the exponential function model can be used to predict the critical time of safety valve rupture and ejection at different distances.Besides,The SOC is proportional to the critical distance of the safety valve cracker and ejection.Secondly,experiment with different horizontal distances between batteries are implemented.For the third battery,the larger the SOC or the larger the d₂,the shorter the critical time of the safety rupture and the larger the critical distance d₁.Simultaneously,inversely proportional to the critical time of the ejection.But,the critical distance of the ejection is the same.The upper batteries has many of the same rules as the third battery:the critical surface temperature of safety valve cracker or ejection is independent of the distance,but inversely proportional to SOC;if the ejection occurs or the safety valve cracker of0%SOC,the total mass loss and maximum mass loss rate are independent of distances,but proportional to SOC.SOC is proportional to the peak concentration of CO and SO₂,and inversely proportional to the peak of HRR and heat released.The lower two THS1 batteries and the first two TIT3 batteries are the same as the radiation intensity of furnace.The experiment found that the two batch batteries have the same aspect:experimental process of different SOC,release rule of CO and SO₂concentration.But there are also different aspects:safety valve cracker and ejection time,maximum surface temperature,mass loss,maximum temperature rise rate and maximum mass loss rate,peak CO and SO₂ concentration.