Biomimetic hierarchical heterogeneity endows layered nanocomposite with excellent mechanical and electrical insulating properties.

Aramid-based nanopapers with high mechanical and electrical insulating properties, together with high-temperature stability, are urgently desired for electrical safety but are challenging to be constructed. Notably, biological materials can adopt different nanoscale building blocks and regulate their spatial distribution to construct hierarchical heterostructure for overall performance optimization. Herein, inspired by biological hierarchical heterogeneity, integrating building blocks of two-dimensional rectorite nanosheet (RNS) and one-dimensional aramid nanofiber (ANF), we construct hierarchically heterostructured nanopapers with RNS-enriched bilateral sublayers and the ANF-enriched inner sublayer. The obtained 5-10-5 heterostructured nanopaper with 20-micrometer thickness through systematic regulation exhibits an impressive combination of breakdown strength (171 kilovolts per millimeter), corona resistance (18.3 hours), and mechanical properties, surpassing homostructured RNS-ANF nanopapers. The enhancement efficiency of corona resistance is orders of magnitude higher than that of reported insulating papers. The breakdown strength and corona resistance can be retained at high values in real-time temperature (up to 150°C). These properties make our biomimetic hierarchically heterostructured nanopaper highly competitive for applications.