Numerical Study of Self-Heating Ignition of a Box of Lithium-Ion Batteries During Storage
- PDF / 1,389,577 Bytes
- 19 Pages / 439.37 x 666.142 pts Page_size
- 43 Downloads / 170 Views
Numerical Study of Self-Heating Ignition of a Box of Lithium-Ion Batteries During Storage Zhenwen Hu , Xuanze He and Guillermo Rein *, Department of Mechanical Engineering, Imperial College London, London, UK Francesco Restuccia, Department of Engineering, King’s College London, London, UK Received: 27 August 2019/Accepted: 11 May 2020
Abstract. Many thermal events have been reported during storage and transport of large numbers of Lithium-ion batteries (LIBs), raising industry concerns and research interests in its mechanisms. Apart from electrochemical failure, self-heating ignition, driven by poor heat transfer could also be a possible cause of fire in large-scale ensembles of LIBs. The classical theories and models of self-heating ignition assume a homogeneous lumped system, whereas LIBs storage involves complex geometry and heterogeneous material composition due to the packaging and insulation, which significantly changes the heat transfer within the system. These effects on the self-heating behaviour of LIBs have not been studied yet. In this study, the self-heating ignition behaviour of a box containing 100 LiCoO2 (LCO) type of cylindrical cells with different insulation is numerically modelled using COMSOL Multiphysics with a multi-step reaction scheme. The model predicts that the critical ambient temperature triggering self-ignition of the box is 125°C, which is 30°C lower than that for a single cell, and the time to thermal runaway is predicted to be 15 times longer. The effects of different insulating materials and packing configurations are also analysed. This work provides novel insights into the self-heating of large-scale LIBs. Keywords: Fire, Lithium-ion battery, TR, Safety, Heat transfer List of Symbols A E DH R W Q T c n cp h
Frequency factor (s-1) Activation energy (J mol-1) Specific heat release )J kg-1) Reaction rate (s-1) Material content (kg m-3) Heating power (W) Temperature (K) Dimensionless concentration Reaction order Heat capacity (J kg-1 K-1) Convection heat transfer coefficient (W m-2K-1) * Correspondence should be addressed to: ; Guillermo Rein, E-mail: [email protected]
1
Fire Technology 2020 k q000 q00 t z
Average heat conductivity (W m-2K-1) Volumetric heat source (W m-3) Heat flux (W m-2) Time (s) Dimensionless SEI thickness
Greek Symbols a q e v
Degree of conversion Average density (kg m-3) Emissivity The volume ratio of battery cells over the box
Subscript 0 a s b air box conv rad sym sei p n e tot a, cr on
Initial state Ambient Boundary at free surface Battery Air The box Convective heat transfer Radiative heat transfer Symmetry boundary SEI decomposition reaction Positive electrode Negative electrode Electrolyte Total reactions Critical state of ambient that can trigger TR Onset state of cell when TR starts to take place
1. Introduction Lithium-ion batteries (LIBs) are a popular type of rechargeable battery which have wide applications in portable devices such as cell phones, cameras, laptops, and even for vehicles and smart grids [1, 2]. However, fire safety issues remain a
Data Loading...
