Enhanced energy density of composite dielectrics at high temperatures by incorporating hydrogen-bonded organic frameworks

With increasing heat resistance requirements of modern power electronics systems, traditional commercial film capacitors have been unable to meet practical needs. Therefore, it has become urgent to develop new dielectrics capable of operating in extreme environments and offering high energy storage density. In this study, we developed polyetherimide (PEI)-based composites incorporating a hydrogen-bonded organic framework (HOF), using 3,5-diamino-1,2,4-triazole (DAT) as a linker between HOF fillers and PEI matrix. This approach exhibits excellent stability due to its eight-fold hydrogen bonding structure. Multi-site reversible dynamic hydrogen-bonding networks of the composites successfully balance the trade-off between breakdown strength ( E b ) and polarization under extreme conditions. The optimized composite (0.2 wt% HOF-DAT) achieves an E b of 578 kV/mm (up from 482 kV/mm for pure PEI). It delivers a high energy storage density ( U e ) of 4.86 J/cm 3 with energy efficiency ( η ) of 90 % at 150 °C—a 113 % improvement over pure PEI. Meanwhile, the composite presents extremely excellent results in the viability test. This work presents an innovative strategy for fabricating dielectrics with high U e and η simultaneously in harsh environments. • HOFs are firstly used to boost dielectric energy storage via multisite H-bonded networks. • Thermally reversible H-bonds resolve breakdown strength vs. polarization trade-off under harsh conditions. • Achieve a high discharge energy density of 4.86 J/cm 3 while efficiency is above 90 %.