Superior Capacitive Energy Storage Enabled by Molecularly Interpenetrating Interfaces in Layered Polymers

Polymer dielectrics are essential for advanced electronics and electrical power systems, yet they suffer from low energy density (U_e) due to their low dielectric constant (K) and the inverse relationship between K and breakdown stength (E_b). Here a scalable approach utilizing the designed molecularly interpenetrating interfaces is presented to achieve all-organic dielectric polymers with high U_e and charge–dischage efficiency (η). Distinctive intermolecular interactions and microstructural changes, as demonstrated experimentally and theoretically, are introduced by the molecularly interpenetrating interfaces, resulting in simultaneous improvements in dielectric responses and mechanical strength while inhibiting electrical conduction – outcomes unattainable in conventional layered polymers. Consequently, exceptional improvments in both K and E_b are achieved, yielding a very high U_e of 22.89 J cm⁻³ with η ≥ 90%, outperforming current layered polymer dielectrics. The bilayers can be easily fabricated into large-area films with high uniformity and outstanding capacitive stability (>500 000 cycles), offering a practical route to scalable high-U_e polymer dielectrics for electrical energy storage.