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.