Corrosion-resistant and heat-dissipative SiOC ultralight lattice for high-temperature EMI shielding

High-temperature electromagnetic interference (EMI) shielding material is essential for intense thermal or electromagnetic radiation applications. Ceramics are promising candidates but are often fabricated with increased density and thickness to achieve sufficient shielding effectiveness (SE). However, we present an unconventional strategy to enhance the SE of ceramics by reducing density realized through hierarchical lattice design. 3D-printed silicon oxycarbide (SiOC) with self-arrayed and corrosion-resistant carbon nanosheets was employed to materialize this design. As the density decreases from 2.73 to 0.53 g/cm³, the SE increases from 12.53 to 27.27 dB. The combined effects of densely arrayed carbon nanosheets and hierarchical design amplify multi-reflection/scattering, enabling enhanced EMI shielding at reduced density. Furthermore, this structure is capable of operation at 600 °C and oxygen corrosion environment even at an ultralow density of 0.29 g/cm³, achieving over 99 % shielding efficiency. It exhibits a low thermal expansion coefficient of 1.41 × 10⁻⁶/K at 600 °C, along with compressive strength, Young’s modulus, and energy absorption of 6.38 MPa, 3.02 GPa, and 8.14 kJ/cm³, respectively, ensuring mechanical, dimensional, and shielding robustness. The interconnected hollow spaces and exposed surfaces facilitate both active and passive heat dissipation, preventing thermal failure and extending the operational lifespan. Under airflow, the heated structure cools to 46.6 °C within 25 s, effectively reducing the operating temperature. This strategy provides a straightforward approach for fabricating high-temperature and lightweight EMI shielding ceramics through structural optimization, underscoring its potential for performance enhancement, cost reduction, and application expansion for extreme environments.