# A Review of Experimental and Numerical Studies of Lithium Ion Battery Fires
## 5 Heat Release Rate
### HRR and TTI Measured Data for 18650 Batteries  
Fu [6] studied the burning behaviors of commercial 18650 2.6 Ah LIBs, (Sanyo-UR18650 FM). The cathode material used was LCO with a graphite anode and electrolyte consisting of organic solvents and inorganic salts. Five tests were conducted at various SOC (0, 50, 60, 70, and 100%) exposing the LIBs to an incident heat flux of 50 kW m\({}^{-2}\) using a cone calorimeter in accordance with the ISO 5660-1 with an additional two tests exposing the LIBs at 100% SOC heat fluxes of 30 and 60 kW m\({}^{-2}\). The results are presented in Table 10. The normalized HRR data are derived from the HRR data by dividing by the battery surface area. The results at 50 kW m\({}^{-2}\) indicate that SOC and the time to peak HRR and the magnitude of the peak HRR for the batteries at 100, 70, and 65% show a similar relationship. The batteries at 0 and 50% SOC, however, show no disposition to this relationship in terms of either time to peak HRR or peak HRR value. LIBs exposed to increased heat flux were shown to reach peak HRR faster and have a peak HRR of greater magnitude; the peak HRR (9.1 kW) of the LIB, when exposed to 60 kW m\({}^{-2}\), was considerably greater than the peak HRR of the LIBs when exposed to heat fluxes of 50 and 30 kW m\({}^{-2}\) (6.8 and 6.2 kW, respectively). The experimental results indicate that the peak HRR increase as a function of incident heat flux as the chemical reactions between \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Solvent**} & **Molecular** & **Flash** & **Boiling** & \(\Delta\mathrm{H_{c}}\) & \(\Delta\mathrm{H_{vap}}\) & \(\Delta\mathrm{H_{c}}\mathrm{G^{0}}\) \\  & **Formula** & **point (\(\mathrm{\SIUnitSymbolCels}\))** & **Point (\(\mathrm{\SIUnitSymbolCels}\))** & **(MJ kg\({}^{-1}\))** & **(MJ kg\({}^{-1}\))** & **(kJ mol\({}^{-1}\))** \\ \hline EC [136] & \(\mathrm{C_{3}\,H_{4}\,O_{3}}\) & 146 & 248 & 12.66 & 0.62 & \(-\)276.19 \\ DMC [136] & \(\mathrm{C_{3}\,H_{6}\,O_{3}}\) & 18 & 91 & 14.48 & 0.43 & \(-\)364.54 \\ EMC [136] & \(\mathrm{C_{4}\,H_{8}\,O_{3}}\) & 23 & 110 & 18.41 & 0.34 & \(-\)356.12 \\ DEC [137] & \(\mathrm{C_{5}\,H_{10}\,O_{3}}\) & 445 & 126 & 21.63 & 0.34 & \(-\)347.70 \\ PC [137] & \(\mathrm{C_{4}\,H_{6}\,O_{3}}\) & 455 & 242 & 16.56 & 0.55 & \(-\)275.48 \\ EA [137] & \(\mathrm{C_{4}\,H_{8}\,O_{2}}\) & 427 & 77 & 23.77 & 0.35 & \(-\)251.12 \\ \hline \hline \end{tabular}  
* EC is ethylene carbonate, DMC is dimethyl carbonate, DEC is diethyl carbonate, PC is propylene carbonate, EA is ethyl acetate, \(\Delta\mathrm{H_{c}}\) is the heat of combustion, \(\Delta\mathrm{H_{vap}}\) is the heat of vaporization, and \(\Delta\mathrm{G^{0}}\) is the standard Gibbs free energy of formation.  
\end{table} 
Table 9: Thermochemical and physical properties of the commercially available solvents [136,137]. LIB materials are of greater intensity. This trend was also reported by [PERSON] et al. [139] and thought to be due to the blowing off the fire by the high-speed gas ejection during the TR [139], incomplete combustion of gases as the sudden explosion limits the oxygen consumption [6], and the internally released oxygen involved in the combustion in the relatively short burning process [6]. [PERSON] [85] reported on the fire behavior of LIBs at varying states of charge induced by high incident heat fluxes. Bench-scale testing using a cone calorimeter in accordance with the ISO 5660 standard was conducted with the objective to investigate the influence of SOC and external heat flux on the combustion behavior, TTI, and HRR. The fire risk of the LIBs at different SOC and under various heat fluxes was also analyzed. Samsung 18650 LIBs with (NMC) cathode, graphite anode, and an electrolyte consisting of organic solvent and inorganic salt were tested. The LIBs were provided with a burst disk as a safety vent to allow venting in abuse conditions.