Single-Crystalline BaZr0.2Ti0.8O3 Membranes Enabled High Energy Density in PEI-Based Composites for High-Temperature Electrostatic Capacitors

Dielectric capacitors are promising for high power energy storage, but their breakdown strength (E-b) and energy density (U-e) usually degrade rapidly at high temperatures. Adding boron nitride (BN) nanosheets can improve the E-b and high-temperature endurance but with a limited U-e due to its low dielectric constant. Here, freestanding single-crystalline BaZr0.2Ti0.8O3 (BZT) membranes with high dielectric constant are fabricated, and introduced into BN doped polyetherimide (PEI) to obtain laminated PEI-BN/BZT/PEI-BN composites. At room temperature, the composite shows a maximum U-e of 17.94 J cm(-3) at 730 MV m(-1), which is more than two times the pure PEI. Particularly, the composites exhibit excellent dielectric-temperature stability between 25 and 150 degrees C. An outstanding U-e = 7.90 J cm(-3) is obtained at a relatively large electric field of 650 MV m(-1) under 150 degrees C, which is superior to the most high-temperature dielectric capacitors reported so far. Phase-field simulation reveals that the depolarization electric field generated at the BZT/PEI-BN interfaces can effectively reduce carrier mobility, leading to the remarkable enhancement of the E-b and U-e over a wide temperature range. This work provides a promising and scalable route to develop sandwich-structured composites with prominent energy storage performances for high-temperature capacitive applications.

Automated summary

In this study, boron nitride (BN) nanosheets were added to polyetherimide (PEI) to improve the breakdown strength (E-b) and high-temperature endurance, while freestanding single-crystalline BaZr0.2Ti0.8O3 (BZT) membranes with high dielectric constant were fabricated to enhance the energy density (U-e). The resulting laminated PEI-BN/BZT/PEI-BN composites showed a maximum U-e of 17.94J cm(-3) at 730 MV m(-1) at room temperature, which is more than double that of pure PEI. The composites also demonstrated excellent dielectric-temperature stability between 25 and 150 degrees C, with an outstanding U-e = 7.90 J cm(-3) at 650 MV m(-1) under 150 degrees C, surpassing other high-temperature dielectric capacitors reported thus far. Phase-field simulation revealed that the depolarization electric field at the BZT/PEI-BN interfaces effectively reduced carrier mobility, resulting in improved E-b and U-e over a wide temperature range. This work provides a promising and scalable route for developing sandwich-structured composites with remarkable energy storage performances for high-temperature capacitive applications.