Interface Rectification via Roll‐to‐Roll Dual‐Confinement Nanocoatings for High‐Temperature Polymer Capacitors

Polymer film capacitors are indispensable for energy storage and power conversion, yet their energy density and efficiency deteriorate rapidly at elevated temperatures. At temperatures relevant to wide-bandgap semiconductor electronics (>150°C), heat-resistant polymer films must be heavily derated to avoid premature aging due to intensive hot-carrier injection. Inspired by multilayered barrier structures in nature, we developed a scalable roll-to-roll self-assembled organic-inorganic nanolaminate coating that significantly enhances the high-temperature dielectric performance of polymer films. The nanolaminate architecture introduces dual confinement mechanisms: nanoconfinement of the polymer binder suppresses chain motion and enhances thermal stability, while anisotropic carrier relaxation within two-dimensional nanoclay nanosheets impedes through-plane hot-carrier transport. Together, these effects synergistically establish an interface-rectification mechanism that promotes in-plane energy dissipation and suppresses carrier injection at electrode-polymer interfaces. At 150°C, the coating significantly reduces the pre-breakdown conduction current of polyetherimide (PEI), increases the breakdown strength from 450 to 501 MV/m, and improves the discharged energy density at 95% efficiency by 105%. Furthermore, roll-to-roll-coated PEI capacitors exhibit a 45-fold lifetime enhancement at 150°C and 180 MV/m-a design field previously sustained only by BOPP below 60°C. This work provides a scalable and technology-ready strategy for high-temperature, high-density polymer capacitive energy storage.