Ziwei Tian, Jie Zheng, Haidong Wang, Guang Zhang, Yanxi Chen, Ronghua Pang, Quan Zheng, Xin Liu, Songzheng Yu, Guihua Liu, Yiwei Liu, Jianzhong Liu, Yang Li, Bingyang Cao, Peng Zhang, Ziyuan Ouyang
Abstract The development of high-efficiency thermal insulation materials is crucial for terrestrial and space applications under extreme conditions. Synthetic aerogels, featuring porosities up to 99%, can reach the values of ~10 mW m −1 K −1 under vacuum. However, whether natural materials can achieve this performance remains an open question. Here, we report lunar agglutinates from the Chang’E-5 mission that exhibit thermal conductivities as low as ~8 mW m − 1 K − 1 under vacuum, surpassing most high-performance aerogel materials — at modest porosities of only 7–30%. Integrated structural characterizations and atomic-to-mesoscale simulations demonstrate that the space-weathering-forged multiscale voids and multiphase interfaces collaboratively suppress phonon transport within agglutinate particles, leading to their ultra-low thermal conductivities. These natural structures demonstrate a non-porosity-dominated thermal insulation mechanism. The findings redefine the microstructural design principles for super-insulating materials and provide a particle-scale explanation for the ultralow thermal conductivity of lunar regolith.