A Flame‐Retardant, Thermal‐Insulating Wood‐Derived Aerogel toward All‐Season Thermal Management

Abstract Passive radiative cooling (PRC) is widely regarded as a transformative and sustainable cooling technology for diverse applications. However, current PRC materials suffer from a range of issues, including overcooling during night/winter, fire risks, etc. Herein, a flame‐retardant and thermal‐insulating wood‐based high‐performance PRC aerogel is designed to overcome these challenges. The hierarchical aerogel is rationally constructed by integrating highly efficient solar‐scattering silica nanoparticles and dual‐function magnesium‐aluminum layered double hydroxide nanoflakes (serving as both thermal emitters and flame retardants) into a wood‐derived porous cellulose scaffold. This structure endows the aerogel with exceptional optical selectivity, achieving a high solar reflectance of 96.43% and a high thermal emittance of 97.49% in the atmospheric transparency window. Therefore, the aerogel ultimately enables outstanding all‐season thermal management, including a substantial sub‐ambient cooling of 15.6 °C during summer daytime and a considerable net warming effect of 2.1 °C on winter nights, supported by its ultralow thermal conductivity (0.043 W m −1 K −1 ). Critically, the aerogel exhibits superior fire safety, with a low heat release rate and negligible smoke production. This work presents a promising strategy toward next‐generation safe and low‐cost thermal‐managing materials, demonstrating immense potential for energy‐saving buildings, cold‐chain logistics, and personal thermal management.