Large-scale assembly of isotropic nanofiber aerogels based on columnar-equiaxed crystal transition

Abstract

Ice-templating technology holds great potential to construct industrial porous materials from nanometers to the macroscopic scale for tailoring thermal, electronic, or acoustic transport. Herein, we describe a general ice-templating technology through freezing the material on a rotating cryogenic drum surface, crushing it, and then re-casting the nanofiber slurry. Through decoupling the ice nucleation and growth processes, we achieved the columnar-equiaxed crystal transition in the freezing procedure. The highly random stacking and integrating of equiaxed ice crystals can organize nanofibers into thousands of repeating microscale units with a tortuous channel topology. Owing to the spatially well-defined isotropic structure, the obtained Al2O3·SiO2 nanofiber aerogels exhibit ultralow thermal conductivity, superelasticity, good damage tolerance, and fatigue resistance. These features, together with their natural stability up to 1200 °C, make them highly robust for thermal insulation under extreme thermomechanical environments. Cascading thermal runaway propagation in a high-capacity lithium-ion battery module consisting of LiNi0.8Co0.1Mn0.1O2 cathode, with ultrahigh thermal shock power of 215 kW, can be completely prevented by a thin nanofiber aerogel layer. These findings not only establish a general production route for nanomaterial assemblies that is conventionally challenging, but also demonstrate a high-energy-density battery module configuration with a high safety standard that is critical for practical applications.

Continuous Rapid Fabrication of Ceramic Fiber Sponge Aerogels with High Thermomechanical Properties via a Green and Low-Cost Electrospinning Technique

“…Particularly, ceramic aerogels show a rapid heat transfer pathway and extremely low thermal conductivity due to their unique 3D interconnected porous network structure that can lock gas molecules. , Researchers have proven the exceptional performance of ceramic aerogels in blocking thermal runaway propagation. Moreover, the lightweight ceramic aerogels have low impact on decreasing the energy density of battery packs. − Ceramic aerogels are mostly constructed from granular powders, and the production involves sol–gel, aging, modification, and drying. , The drying process is crucial to the synthesis of aerogel, and the mainstream drying processes include supercritical drying and atmospheric drying. By slow drying of the liquid components without degrading the solid skeleton structure, ceramic aerogels with extremely high porosity, large specific surface areas (SSA), and low densities can be formed.…”