A Detailed Finite Element Model of Internal Short Circuit and Venting During Thermal Runaway in a 32650 Lithium-Ion Batt
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A Detailed Finite Element Model of Internal Short Circuit and Venting During Thermal Runaway in a 32650 Lithium-Ion Battery Bing Wang, Changwei Ji*, Shuofeng Wang and Shuai Pan, College of Environmental and Energy Engineering, Beijing Lab of New Energy Vehicles and Key Lab of Regional Air Pollution Control, Beijing University of Technology, Beijing 100124, People’s Republic of China Received: 2 October 2019/Accepted: 31 March 2020
Abstract. The frequent accidents of power lithium-ion battery have become the major reason to hinder the development of electric vehicles. In this paper, the thermal runaway process for a 32650 battery is analyzed based on 300°C oven heating experiment in adiabatic rate calorimeter, the rise of temperature, the drop of voltage and the leakage of electrolyte are observed before exploding, which could be used as predictor variables for thermal runaway warning. A large number of smoke releases and diffuses after explosion, which could be utilized as a criterion for determining the explosion. And a lumped chemical reaction kinetics model coupled with three-dimensional heat transfer model is constructed for further discussion. The thermal runaway process of the battery could be accurately calculated by the coupled model. Thermal radiation plays a more important role in heat transfer than heat convection in the process of thermal runaway. The explosion happens when the temperature achieves around 230°C, and the active material mainly starts to decompose at this moment. Keywords: Power lithium-ion battery, Thermal runaway, Oven heating, Finite element method List of Symbols Ax Cpbat Ea,x h Hx I j Mbat mx Qdec Qheat Qisc
Reaction frequency factor (s-1) Heat capacity of the battery (J kg-1 K-1) Reaction activation energy (kJ mol-1) Heat-transfer coefficient (W m-2 K-1) Reaction heat (J kg-1) Short-circuit current (A) Dimensionless volume fraction of generated SEI Mass of this battery (kg) Reaction order Total heat generation of all abuse reactions (W m-3) Heating power (W) Heat generation during ISC (W)
* Correspondence should be addressed to; Changwei Ji, E-mail: [email protected]
1
Fire Technology 2020 Rx Rg Rbat Risc S t T Tamb DT v Wx zx
Reaction rate of each abuse reaction (s-1) Universal gas constant (J mol-1 K-1) Resistance of the battery (X) Equivalent ISC resistance (X) Area of battery surface (m2) Time (s) Absolute temperature (K) Ambient temperature (K) Rise of battery temperature (K) Voltage (V) Mass fraction of reacting material (kg m-3) Dimensionless volume fraction
Greek Letters e qbat r kbat b
Emissivity Density of battery (kg m-3) Stefan–Boltzmann constant (W m-2 K-4) Heat conductivity of battery (W m21 K21) Efficacy coefficient
Subscripts and Superscripts 0 sei e pvdf ne pe
Initial or equilibrated state Solid–electrolyte interface Electrolyte Poly (vinylidene fluoride) Negative electrode Positive electrode
Acronyms and Abbreviations 3D ARC COMSOL ISC NE PE PVDF SOC SEI VSP2
Three dimensional Adiabatic rate calorimeter Inc. Sweden computer-aided engineering software developer
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