Concrete-inspired closet packing designed Al-doped silica aerogel coatings for fireproof and thermal insulation protection

Modern civil and industrial fire protection applications demand increasingly rigorous performance standards for thermal insulation materials. While aerogel-based coatings have emerged as promising candidates in recent years, their effectiveness remains constrained by limited aerogel loading capacities, which fundamentally restricts their thermal insulation performance. Here, we fabricate an Al-doped silica aerogel coating inspired by the closet packing design of concrete. The result coatings’ aerogel content could up to 95 %–98 %, which is far beyond the present reported works. Besides, the coating showed ultra-lightweight property (263.36 ± 4.56 mg/cm 3 ), outstanding thermal insulation performance (29.75 mW m −1  K −1 at 25 °C, 168.97 mW m −1  K −1 at 1000 °C), and could work at 800 °C for long-term with backside temperature 258 °C (4 mm thickness). Meanwhile, the result coating showed super fire retardant compared to commercial aerogel coating and fire intumescent coating. This large aerogel content coating with excellent fireproof performance can perfectly match the advanced fire protection requirements, and provide an idea for improving thermal insulation performance of coatings.