UV Induced Surface Crosslinked Polyarylether Sulfone Films for High‐Temperature Capacitor Energy Storage Produced via Roll‐to‐Roll Process

ABSTRACT High‐temperature capacitive energy storage demands that the dielectric film maintain low conduction loss and superior thermal stability. However, it is difficult for traditional thermal‐resistant polymers to maintain low conductive loss at high temperatures. To address the issue, this work proposes a UV‐induced surface crosslinking strategy for high‐temperature resistant polyaryl ether, which suppresses charge transfer to reduce conduction loss and avoids film denaturation caused by bulk crosslinking, achieving roll‐to‐roll industrial production of films. First, a novel poly(aryl ether) PPES‐ADM is prepared by introducing the non‐planar structure of adamantane into poly(phthalazinone ether sulfone) (PPES) through molecular engineering, and breaking the strong π–π conjugation. Then, the adamantane and cyclic ketone in the phthalazinone moiety on the film surface can be cross‐linked by UV induced to suppress charge injection from the electrode. Therefore, the UV‐induced film exhibits ultrahigh discharge energy density ( U e ), with 10.20 and 7.91 J cm −3 at room temperature and 150 ° C, respectively, which are 1.84 times and 2.16 times higher than those of PPES, respectively. Notably, the UV‐induced film exhibits superior self‐healing properties, presenting excellent cycling stability. The large‐scale film produced by roll‐to‐roll production, with its low‐cost advantage, offers practical feasibility for commercial applications.