Optimizing the conjugated structure of aromatic polyurea for high-temperature capacitive energy storage.

This article focuses on the design and optimization of aromatic polyurea (PU) dielectrics for high-temperature energy storage applications. By introducing different bridge linkages—ether, methylene, and isopropyl—between adjacent benzene rings, the study modulates the dihedral angles to reduce conjugation, thereby enhancing thermal stability, suppressing leakage conduction, and improving breakdown strength. The PU containing the isopropyl moiety exhibits the best performance, achieving discharged energy densities (Ue) of 5.1 J/cm³ at 30 °C and 2.1 J/cm³ at 150 °C with charge–discharge efficiencies above 90%, outperforming common high-temperature polymer dielectrics. The findings highlight the critical role of controlling interactions between conjugated rings in polymers to advance scalable dielectric materials suitable for harsh electrical and thermal environments.