# A Review on the Thermal Hazards of the Lithium-Ion Battery and the Corresponding Countermeasures
## 3 The Causes of Thermal Hazards Associated with Lithium-Ion Batteries
### Physical Factor  
The destructive deformation of battery caused by an applied force is a common feature of physical factor. Where, vehicle collision/crash and penetration of battery are the typical conditions for physical failure. Furthermore, the volume expansion of electrode materials and stress generation within battery may also lead to physical failure. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Classification** & **No.** & **Date** & **Location** & **Accident Reply** \\ \hline \multirow{8}{*}{Mobile telephone} & 1 & 2016.824 & Korea & The first explosion of a Note 7 in the world [46] \\  & 2 & 2016.918 & China & The first explosion of a Note 7 in China [46] \\  & 3 & 2016.10.10 & China & An iPhone 7 exploded and hurt the user [47] \\  & 4 & 2016.10.14 & China & A Huawei 9 exploded during charging [48] \\  & 5 & 2016.10.17 & Australia & An iPhone 7 caught fire which then, burned a car [49] \\  & 6 & 2018.19 & Switzerland & An iPhone exploded when replacing the battery, which caused an \\  & 7 & 2018.110 & Spain & An iPhone exploded which caused thick smoke inside the store [50] \\  & 8 & 2018.12.30 & America & An iPhone X5 Max self-ignited and burned the user [51] \\ \hline \multirow{8}{*}{EV} & 1 & 2016.1.1 & Norway & A Tesla Model S caught fire during charging [52] \\  & 2 & 2016.51.4 & China & An EV bus caught fire because of battery pack short-circuit [52] \\  & 3 & 2016.97 & Netherlands & A Tesla Model S crushed to a tree which caused the battery to catch fire, resulting in the death of the driver [52] \\  & 4 & 2017.15 & China & An EV bus self-ignited during driving [53] \\  & 5 & 2017.21 & China & A Tesla Model X caught fire after erxing [53] \\  & 6 & 2017.51 & China & An EV bus self-ignited during charging [53] \\  & 7 & 2018.32.24 & America & A Tesla Model S caught fire whilst stationary [54] \\  & 8 & 2018.52.1 & China & An EV bus self-ignited during driving [54] \\ \hline \multirow{8}{*}{Airplane} & 1 & 2010.9.3 & The United & A Boeing 787 crashed due to the battery catching fire, which caused \\  & 2 & 2013.17 & America & The battery pack caught fire and filled the cabin of a Boeing 787 with smoke [56] \\ \cline{1-1}  & 3 & 2013.1.16 & Japan & The battery pack caught fire during a Boeing 787 flight from Yamaguchi-Ube to Tokyo [56] \\ \cline{1-1}  & 4 & 2014.4 & Australia & A Boeing 737 caught fire due to the short-circuit of the battery inside a \\ \cline{1-1}  & & & & trunk [57] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Selected incidents of lithium-ion battery failure in recent years. As seen in Table 1, many safety-related incidents involving the batteries of EVs took place after deformation. It reveals that during an accident involving the vehicle, it is possible for a single battery or a battery pack to deform under the effect of an external force. The deformation of battery may result in dangerous consequences: (1) the electrodes can come into contact causing an internal short circuit and (2) the flammable electrolyte leaks which may induce a fire. Penetration, another common physical phenomenon may occur if the battery is affected by sharp objects. It is generally listed in the test standards of the LIB, i.e., GB/T 31485-2015, SAE J2464-2009 etc., to trigger the internal short circuit. Compared with collision or crash, penetration may result in more severe consequences due to the severity of the internal short circuit. In this case, severe short-circuit of the battery will rapidly take place and then severe heat release, combustion and even explosion may occur. As known, the compressive stress reached during lithiation and the tensile stress reached during delithiation are significant inside battery [63; 64]. Such large stress cycling over extended lithiation/delithiation cycles will invariably lead to fatigue damage, leaving battery materials susceptible to fracture and pulverization.