Pinning and elongating of electric treeing induced by wrinkled nanosheets in polymer dielectrics towards significantly enhanced high-temperature energy storage performance

The polyetherimide composite with 0.2 wt% alumina nanosheets exhibits pinned, elongated breakdown paths due to wrinkles, achieving an ultrahigh energy density of 8.27 J cm –3 (>90% efficiency) at 150 °C, 420% that of pure polyetherimide film.