Hierarchical Cellulose Superinsulation Membrane

The environment‐friendly components coupled with the ability to mimic the simplicity and originality of nature necessitate advanced sustainable materials with structural capabilities for energy‐efficient applications. The use of feedstock deriving from plant‐based, renewable organic material to produce nanofibril that embodies enhanced insulating properties and high mechanical strength constitutes an efficient development strategy. Herein, a free‐standing, hierarchical superinsulation membrane by leveraging the principle of the bottom‐up method is reported. The electrospun cellulose nanofibrils/aerogel‐based core layer provides exceptional thermal properties with its thermal conductivity of 10.2 mW m⁻¹K⁻¹. The lightweight, flexible, and durable paper‐like membrane features a tensile strength of 11.3 MPa and a bending rigidity in the order of 4.6 cN mm⁻¹. The hydrophobic superinsulation membrane material also exhibits a ΔT of ≈25 °C under continuous sunlight illumination and allows thermal runaway mitigation of rechargeable lithium‐ion batteries. All the aforementioned properties position this hybrid superinsulation membrane as a promising material for energy‐saving thermal management applications.