Scalable Ultrathin All‐Organic Polymer Dielectric Films for High‐Temperature Capacitive Energy Storage

Abstract

The miniaturization of electronic devices and power systems for capacitive energy storage under harsh environments requires scalable high‐quality ultrathin high‐temperature dielectric films. To meet the need, ultrasonic spray‐coating (USC) can be used. Novel polyimides with a dipolar group, CF3 (F‐PI), and all‐organic composites with trace organic semiconductor can serve as models. These scalable high‐quality ultrathin films (≈2.6 and ≈5.2 µm) are successfully fabricated via USC. The high quality of the films is evaluated from the micro‐millimeter scale to the sub‐millimeter and above. The high glass transition temperature Tg (≈340 °C) and concurrent large bandgap Eg (≈3.53 eV) induced by weak conjugation from considerable interchain distance (≈6.2 Å) enable F‐PI to be an excellent matrix delivering a discharge energy density with 90% discharge efficiency Uη90 of 2.85 J cm−3 at 200 °C. Further, the incorporation of a trace organic semiconductor leads to a record Uη90 of ≈4.39 J cm−3 at 200 °C due to the markedly enhanced breakdown strength caused by deep charge traps of ≈2 eV. Also, a USC‐fabricated multilayer F‐PI foil capacitor with ≈85 nF (six layers) has good performance at 150 °C. These results confirm that USC is an excellent technology to fabricate high‐quality ultrathin dielectric films and capacitors.

Molecular Trap Engineering Enables Superior High‐Temperature Capacitive Energy Storage Performance in All‐Organic Composite at 200 °C

“…Notably, it is clearly seen that the composites with ITIC‐Cl outperform the current all‐organic dielectric polymers and composites at 10 Hz (Figure 3b,d). [ 15,21–25,30–34 ] It is noteworthy that such high U e at η > 90% achieved at 200 °C is even comparable to the room‐temperature value of BOPP (4.0 J cm −3 ). [ 14 ] Note that the energy loss derived from the D ‐ E loops is highly related to the applied frequency since high‐frequency results in low energy loss, high η, and high U e .…”

“…Here we present the polymer/organic semiconductor composites with superior capacitive energy storage performance at 200 °C. Different from earlier works, [21,22,25] we focus on the effect of the structure and properties of molecular semiconductors on the capacitive performance of the composites. A new generalizable design principle (i.e., substituent engineering of organic semiconductors) is proposed to optimize the high-temperature capacitive energy storage performance.…”

Designing tailored combinations of structural units in polymer dielectrics for high-temperature capacitive energy storage

“…S4). Impressively, the U e90 of the polymer reported in this work is as high as 5.3 J/cm 3 , surpassing all the existing pure polymers and their composites 10,11,15,17,18,23,[33][34][35][36] . Note that, although the previous best hightemperature polymer dielectric (cyclic-olefin polymer) 23 delivers a high U e (6.5 J/cm 3 ) at 200 °C that is comparable to the PI-oxo-iso, its U e90 is merely around 2 J/cm 3 , suggesting that the PI-oxo-iso would significantly outperform the cyclic-olefin polymer at the temperature and electric field extremes.…”

High‐Entropy‐Nanofibers Enhanced Polymer Nanocomposites for High‐Performance Energy Storage

“…Modern electric devices and power systems require dielectric capacitors that are able to work stably in high temperatures over 150 °C. [44,45] Thus, the temperature stability of the composite films was evaluated by measuring their Weibull breakdown strength at different temperatures (Figure 5a). As expected, a weak degradation of 9.8% for E b was achieved when the working temperature increased from 25 to 200 °C, while the value for PEI, PEI/LEnf, and PEI/MEnf was 30.8%, 30.6%, and 27.0%, demonstrating the excellent temperature stability of the PEI/HEnf composites.…”