## 3 Results
### TR Propagation Barrier with Only Insulation Layer Added  
The TR propagation time between cells is shown in Figure 3a, and the propagation test without the insulation layer is taken as the control group. The comparative analysis shows that the thermal propagation time of the module with the insulation layer is much longer than that of the module without the insulation layer. The effect of the glass fiber aerogel insulation layer is better than that of the nano-ceramic fiber insulation layer, while \begin{table}
\begin{tabular}{c c c} \hline \hline
**T\({}_{1}\) (Temperature of Initiation of Autogenic Heat)** & **T\({}_{2}\) (TR Trigger Temperature)** & **T\({}_{3}\) (TR Maximum Temperature)** \\ \hline
84 \({}^{\circ}\)C & 147 \({}^{\circ}\)C & 660 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The characteristic temperature of TR. the composite phase change insulation layer has the best effect, and its thermal spread inhibition effect is greatly improved compared with the first two materials. However, regardless of the kind of insulation layer that is used, the battery module has completed thermal spread; the difference is expressed in the spread time. The battery module of the composite phase change insulation layer demonstrates a good effect in restraining TR propagation. The thermal propagation test shows that the composite phase change insulation layer has good phase change heat absorption and heat insulation performance and that it can effectively delay the TR propagation of large-capacity ternary LIBs. In addition, under normal conditions, the composite phase change insulation material has good thermal conductivity, which further ensures its reliability and practicability. The temperature characteristics of the different thermal insulation materials are shown in Figure 3b-d. According to the temperature characteristics diagram, the insulation layer of different materials has a significant influence on the heat spread between batteries. Compared with no barrier, as described in Section 2.1, when the nano-ceramic fiber insulation  
Figure 3: (**a**) Cell-to-cell TR propagation time; (**b**) TR temperature rise diagram of battery module using nano-ceramic fiber insulation layer; (**c**) TR temperature rise diagram of battery module using glass aerogel insulation layer; (**d**) TR temperature rise diagram of battery module using phase change insulation layer; (**e**) TR propagation phenomenon using different insulation layers; (**f**) maximum temperature at each measuring point. layer and glass fiber aerogel insulation layer are used, the heat transfer between adjacent cells is delayed to a certain extent; the temperature that triggers TR is relatively high (280 \({}^{\circ}\)C), and the rise rate is slow. When the composite phase change material insulation layer is used, the phase change heat absorption occurs in the insulation layer, delaying the triggering of heat spread between the batteries; consequently, the second battery can maintain a low temperature within a certain period of time, which shows that the volatilization of the phase change material effectively reduces the surface temperature of the battery. With the consumption of phase change materials, the heat absorption layer cannot play a role. The temperature of the battery wall gradually rises to the TR triggering temperature, which triggers TR. Figure 3e fully records the phenomenon that occurs when each cell in the battery module triggers TR. By observing the experimental phenomenon, it can be seen that when different insulation layers are used, the situation in which TR occurs in the first battery is different. In the nano-ceramic fiber insulation layer module and the glass fiber aerogel insulation layer module, when TR occurs, the locations of explosion and fire are located at different side poles; in the composite phase change material insulation layer battery module, a strong flame and a lot of smoke erupt from the bottom side of the first violent explosion, followed by the explosion of the other surfaces.