In the previous issue, we discussed the thickening and thixotropy of fumed silica in polyurethane adhesives for power batteries. Similarly, fumed silica has a good effect on improving its mechanical properties and thermal storage properties in polyurethane adhesives.

2、 Effect of Fusil 615 and its competitors on the mechanical properties of polyurethane adhesive

A special structure is formed between the surface of fumed silica Fusil 615 and the adhesive molecules. Fusil 615 is uniformly dispersed in the power battery adhesive, and a large number of organic polymer chain segments are wrapped and wrapped on the fumed silica particles in the adhesive, changing the internal structure of the adhesive and causing changes in material properties, resulting in improved mechanical properties of the material. From Table 2, it can be seen that adding fumed silica to the power battery adhesive can significantly improve the tensile and shear strength of the adhesive. Compared with competitors A and B with the same amount of addition, Fusil 615 shows better results in improving the tensile and shear strength of the power battery adhesive.

3、 Effect of Fusil 615 and its competitors on the thermal storage performance of polyurethane adhesive

The thickening effect of gas-phase silica itself increases the viscosity of the system and reduces the settling rate of the pigments and fillers. On the other hand, it increases the yield value of the system. The force of the pigments and fillers itself is below the yield value, and the viscosity is close to infinity. After reaching the yield value, the liquid begins to flow. Therefore, during long-term storage or high-temperature environments, it is necessary to prevent or at least slow down the settling of pigments and fillers in the colloid. From Figure 1, it can be seen that at a temperature of 50 ℃, after 7 days without the addition of fumed silica, the power battery adhesive experienced significant sedimentation. Fusil 615, competitor A, and competitor B did not show significant sedimentation, indicating that the fumed phase can significantly improve the anti sedimentation performance of the power battery polyurethane adhesive. According to Table 3, it can be seen that the thermal storage performance of each component of Fusil 615 is equivalent to that of competitor A, and compared to competitor B, Fusil 615 has better thermal storage performance.

Conclusion: The application of treated fumed silica (Fusil 615) in polyurethane adhesive for power batteries can endow the adhesive with good thickening and thixotropy, prevent dripping of the adhesive during construction, improve anti sagging, improve construction convenience, and increase efficiency. At the same time, it can improve the tear resistance and tensile elongation of the power battery adhesive, enhance the mechanical properties of the adhesive, and play a reinforcing role. Through a 7-day heat storage experiment at 50 ℃, Fusil 615 has shown good anti settling effect and has certain advantages compared to competitors. It can vigorously promote the application of Fusil 615 in power battery adhesives and improve the utilization of domestic fumed silica raw materials for adhesives.