Topological Engineering of Filler Distributions in Dielectric Composites to Boost High-Temperature Capacitive Energy...

Polymer dielectrics, essential for thin-film capacitors, face challenges of excessive leakage current at elevated temperatures. By incorporating the fillers with high electron affinity, they can function as effective electron-trapping centers; however, their spatial distribution also affects both electron transfer and breakdown pathways. Herein, we fabricate five-layered composite films using poly(m-phenylenetisophthalamide) (PMIA) as the matrix and ZrO₂ as the filler. By optimizing the filler distribution as a Type ∇ pattern, with doping ratios of 1.0, 0.5, 0, 0.5, and 1.0 wt.% (totaling 0.6 wt.%) across five layers, a built-in electric field (E_built-in) forms between adjacent layers due to non-uniform electric field distribution. In addition to the intrinsic trapping effect of fillers, this E_built-in opposes the external electric field near the terminal electrodes, generating a repelling force that further inhibits electron transfer. Consequently, leakage current is reduced by two orders of magnitude compared to the PMIA film. The optimal layered film achieves a maximum discharge energy density (U_max) of 14.01 J cm^-3 at 150°C and 12.75 J cm^-3 at 200°C, while retaining 8.89^- and 5.68 J cm^-3 at 90% efficiency, respectively. This highlights a promising horizon for developing high-temperature dielectric composites via topological engineering of filler distribution.