Dielectric Performance Enhancement of Metallized Polypropylene Films Based on Charge‐Carrier Passivation

ABSTRACT This paper demonstrates that an extremely low‐temperature condition (77 K) significantly enhances the dielectric performance of metallized polypropylene films for pulse capacitors. Compared with 298 K, the film conductivity decreases by nearly three orders of magnitude, and the DC breakdown strength increases from 695.4 to 1031.1 kV mm −1 , corresponding to a 48.3% improvement. Self‐healing measurements further show a noticeably milder process at 77 K, with reduced current peak, released energy, and affected area for each self‐healing event. During charge–discharge cycling under the same operating electric field, the electrode loss rate after 1000 cycles at 77 K is approximately 88% lower than that at 298 K, indicating improved service stability and extended lifetime. Mechanistically, low temperature suppresses electrode‐to‐film charge injection and the thermally activated ionization of internal impurities, lowers the detrapping rate of trapped carriers, and promotes a more ordered and densified spherulitic morphology in polypropylene. These synergistic effects restrict carrier transport and hinder impact ionization, thereby improving dielectric strength and operational reliability.