In the fields of automotive electronics

power electronics

and aerospace

environmental conditions are often extremely harsh

particularly for materials that must endure high temperatures

high power and require high stability. The degradation of capacitance performance in polymer dielectrics under high electric fields and elevated temperatures is primarily attributed to the decrease in breakdown strength. To address this

a synergistic strategy combining molecular traps with adjustments to the conjugated structure has been developed to enhance the high-temperature breakdown strength of polymer dielectrics. To address this

we developed a synergistic strategy combining molecular traps with conjugated structure modulation. Experimental and theoretical analyses reveal that polar groups induce deep electron traps via electrostatic interactions

whereas long-chain flexible groups disrupt the conjugation

which alters charge transport mechanisms. Between aromatic rings in the molecular chain

altering the conductivity mechanism. Furthermore

dihedral angle adjustment regulates trap-hopping distances

enhancing high-temperature breakdown strength. As a result

the combined effects of electronic traps and conjugated structure optimisation lead to a discharge energy density of 7.87 J/cm3 at room temperature and 5.99 J/cm3 at 200°C

which is 60% higher than that of OD–PM. This performance surpasses most current polymer dielectrics. Our work establishes a molecular design framework to advance high-temperature capacitive energy storage in polyimides

with direct relevance to harsh-environment applications.