Integrated Molecular Engineering Strategy in All-Organic Dielectrics for Ultrahigh-Temperature Capacitive Energy Storage

• • The optimized FPE/HAT-CN composite achieves discharged energy densities of 7.31 J cm−3 at 150 °C and 6.14 J cm−3 at 200 °C with energy efficiency ≥90%, surpassing conventional high-temperature polymers and enabling reliable operation in electrified transportation and pulsed power systems. • • HAT-CN is identified as a rare organic filler that simultaneously exhibits high electron affinity (deep-level trapping), large bandgap (strong insulation), and high thermal stability, addressing the fundamental trade-off that has limited previous filler designs. • • The all-organic composite preserves mechanical robustness while suppressing high-temperature conduction loss, offering a scalable and low-cost alternative to inorganic-filled composites that often suffer from processing and reliability issues. • • The synergistic filler design strategy provides a potent pathway to break the longstanding high-temperature performance bottleneck in polymer dielectrics, with potential for industrial adoption in film capacitors operating at ≥150 °C.