Facile synthesis of phenolic-reinforced silica aerogel composites for thermal insulation under thermal-force coupling conditions

The objective of this research was to develop a reinforced silica aerogel composites with enhanced thermal insulation performance under thermal-force coupling conditions. Phenolic-reinforced silica aerogel composites (RAs) were synthesized via a sol-immersion-gel process based on the in-situ polymerization of resorcinol (R), formaldehyde (F), and triaminopropyltriethoxysilane (APTES). Ambient pressure drying (APD) was used to dry the gels. Samples with different carbon/silica ratios, RA12, RA13, and RA14, were synthesized by controlling the R/APTES molar ratio at 1/2, 1/3, and 1/4. The densities of the RA12, RA13 and RA14 samples were 0.32 ± 0.005, 0.34 ± 0.006, and 0.37 ± 0.003 g/cm³. The thermal conductivity of the RA12, RA13, and RA14 samples were 0.024, 0.026, and 0.027 W/(m·K). The existence of the phenolic network favored the mechanical strength of the RAs, RA14 showed compressive strength, tensile strength, and three-point bending strength of 4.3 MPa at 20% strain, 2.4 MPa, and 8.4 MPa at 1.45% strain. The RAs showed excellent thermal insulation performance on a customized apparatus, the back temperature was as low as 219.82 °C and 330.67 °C within 60 min in the environments of 600 °C −0.01 MPa and 600 °C −0.9 MPa. The excellent thermal-shock performance of RAs was also demonstrated under flame exposure from a butane torch, with a temperature difference of 878 °C within 30 min being reported. The excellent thermal insulation performance of RAs under thermal-force coupling conditions reveals a widespread application perspective in the field of new energy vehicles power battery thermal protection.