Single-Crystalline BaZr<sub>0.2</sub> Ti<sub>0.8</sub> O<sub>3</sub> Membranes Enabled High Energy Density in PEI-Based Composites for High-Temperature Electrostatic Capacitors.
basic_science · Level V
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- Record sourced from PubMed, PMID 36872865.
- Also identified by DOI 10.1002/adma.202300962.
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Abstract
Dielectric capacitors are promising for high power energy storage, but their breakdown strength (E<sub>b</sub> ) and energy density (U<sub>e</sub> ) usually degrade rapidly at high temperatures. Adding boron nitride (BN) nanosheets can improve the E<sub>b</sub> and high-temperature endurance but with a limited U<sub>e</sub> due to its low dielectric constant. Here, freestanding single-crystalline BaZr<sub>0.2</sub> Ti<sub>0.8</sub> O<sub>3</sub> (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<sub>e</sub> of 17.94 J cm<sup>-3</sup> at 730 MV m<sup>-1</sup> , which is more than two times the pure PEI. Particularly, the composites exhibit excellent dielectric-temperature stability between 25 and 150 °C. An outstanding U<sub>e</sub> = 7.90 J cm<sup>-3</sup> is obtained at a relatively large electric field of 650 MV m<sup>-1</sup> under 150 °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<sub>b</sub> and U<sub>e</sub> 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.