Scalable anisotropic cooling aerogels by additive freeze-casting

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Building cooling is essential but energy-intensive, impacting carbon neutrality goals.
• Aerogels offer thermal insulation for energy-efficient cooling but often absorb solar heat.
• Scalable aerogel fabrication with consistent properties remains a challenge.

Purpose of the Study:

• To develop a novel anisotropic cooling aerogel panel for efficient building cooling.
• To address limitations of existing aerogels, such as solar heat absorption and scalability.
• To create a material with both thermal insulation and solar reflectivity.

Main Methods:

• Additive freeze-casting technique utilizing boron nitride nanosheets.
• Engineering in-plane aligned pores and pore walls for anisotropic properties.
• Fabrication of decimeter-scale aerogel panels with controlled freezing dynamics.

Main Results:

• Achieved ultralow out-of-plane thermal conductivity (16.9 mW m⁻¹ K⁻¹).
• Obtained high solar reflectance (97%) due to engineered pore walls and nanosheets.
• Demonstrated significant reduction in interior temperature (up to 7 °C lower than commercial silica aerogels).

Conclusions:

• The developed anisotropic cooling aerogel panel effectively minimizes parasitic and solar heat gains.
• Additive freeze-casting enables scalable production of high-performance aerogels.
• This material offers a practical solution for energy-efficient cooling applications in buildings.