Thermal Insulation Efficiency and Mechanisms of Flexible Sandwich Structure.

Thermal insulation layers between batteries are an effective way to reduce the propagation of thermal runaway in lithium-ion batteries. A flexible composite sandwich structure material has been designed for thermal insulation, featuring mica rolls (MRs) as the protective layers and a ceramic fiber felt (CFF) as the core layer. Experimental and numerical simulations demonstrate that at a hot-surface temperature of 900 °C, the cold-surface temperature of the sandwich structure with a 0.3 mm MR and 3.0 mm CFF layer is only 175 °C, which is significantly lower than the 350 °C observed for a standalone 3.0 mm CFF layer under the same conditions. The MR layer effectively shields against flames and impedes heat transfer, while the porous structure of the CFF, enhanced by microcracks and holes, increases heat transfer paths and scatters radiated heat. This synergistic interaction between the MR and CFF layers results in a superior thermal insulation performance. The findings highlight the potential of this sandwich structure in improving the safety and thermal management of lithium-ion batteries and other energy storage systems.