Tuning the Electron Trapping for Enhancing the Dielectric Energy Storage Performance of Polypropylene

ABSTRACT The rapid development of high‐end equipment, such as ultrahigh‐voltage transmission and new energy vehicles, has created a pressing need for thin‐film capacitors with high‐temperature resistance and high energy storage capacity. In this study, 1‐(2,4‐dihydroxyphenyl)‐2‐(4‐hydroxyphenyl) ethyl ketone (DPHPE), a voltage stabilizer with high electrophilic affinity, was introduced into a polypropylene (PP) matrix. Charge traps in the modified matrix effectively captured high‐energy carrier electrons, leading to simultaneous improvements in the high‐temperature resistance, high‐pressure resistance, and energy storage performance of PP. Results show that the breakdown field strength of pure PP is 557 and 435 MV m−1 at 25°C and 105°C, respectively. Moreover, for the PP/DPHPE composites containing 0.50 wt% DPHPE, the breakdown field strength improves by 29.8% and 21.1% compared with pure PP, reaching 723 and 527 MV m−1 at 25°C and 105°C, respectively. Furthermore, the composites achieve a dielectric constant of ~2.7 at 25°C, a dielectric loss of < 0.01, an energy storage density of 7.5 J cm−3 at 600 MV m−1, and an energy release efficiency of 89.3%. This study provides a new insight for constructing all‐organic composite dielectric materials with high‐temperature resistance and high energy storage capacity.