Thermal and mechanical abuse of electric vehicle pouch cell modules

Environmental impacts, pollution sources and pathways of spent lithium-ion batteries

“…Spontaneous ignition of LIBs has also been reported, particularly concerning electric vehicles 135 ; the events leading to this remain essentially unknown, but contamination during production or poor design is often quoted. An increasing and slightly worrying phenomenon is the incidence of fires and explosions in large LIB energy storage systems (LIBESS In essence, LIBs in thermal runaway produce gases that are a mixture including hydrogen, carbon monoxide, carbon dioxide, HF, short-chain alkanes and alkenes, HCN, NO x and droplets of solvent 20,22,138,[140][141][142] , the last giving the mixture the appearance of a white cloud 143 . In broad terms, the composition of the white vapour varies little as a function of cell chemistry, form factor or manufacturer 138 .…”

Plasma arc generated vapour cloud from nail penetration of lithium-ion modules?

“…The remaining compounds included benzene, dimethylsilanediol, styrene, ethylbenzene, and various hydrocarbons in the range of C9 to C14 (i.e., 3,3,5-trimethyl-1-hexene, 2,6,6-trimethyl-dodecane, 2,3,6,7tetramethyl-octane, 2-methyl-decane, 2-methyl-5-propyl-nonane and 4-methyl-undecane). From the literature, the main constituents of the vapour cloud are CO, CO 2 , H 2 and hydrocarbons including the organic solvents [17][18] [19]: in addition, the cloud contains HF [7][20], HCl and HCN [7], SO 2 and NO 2 [7][21],…”

“…When the rate at which the heat is generated exceeds that at which the heat is dissipated, the temperature of the battery increases: eventually, the blast caps on cylindrical and prismatic cells rupture, and pouch cells burst, venting the gases which take with them ne droplets of the solvents. If the resulting vapour cloud ignites immediately (typically associated with States-of-Charge > 50% [7]), long are-like ames are produced with a thin fume: if ignition is delayed, a vapour cloud de agration can occur( [7] and references therein).…”

“…Perhaps a more accurate (but challenging to measure) de nition of TR is when the exothermic processes in a cell become self-sustaining and cannot be stopped. The absence of ame and the temperature failing to achieve the speci ed rate of change have been taken as precluding TR [10] [11] [12], however, work in Newcastle has shown that the nail penetration of 1.67 kWh module comprising eight 56.3 Ah pouch cells at 50% State-of-Charge (SoC) catapults the cells into TR, producing a vapour cloud without ame [7]. This was also the case prior to the explosion of the McMicken LiBESS in Surprise, Arizona in April 2019 [13].…”

“…This is then postulated to initiate exothermic chemical processes involving the electrolyte and binder which generate a range of gases that include: CO, CO 2 , H 2 , HCl, HCN, HF as well hydrocarbons [7[[9][14] [15]. The collapse of the separator then causes signi cant internal short circuit and consequent Joule heating leading to TR, the gases are expelled along with an aerosol of the cathode material and droplets of the organic solvent [7]. However, the various exothermic chemical reactions identi ed as producing the gases irrespective of abuse method[16] are largely conjecture.…”