Enhanced high-temperature capacitive energy storage in PMIA-based dielectric films by tailoring a short-range ordered conformation

Abstract

Polymer-based film capacitors are increasingly demanded for energy storage applications in advanced electric and electronic systems. However, the inherent trade-offs among heat tolerance, dielectric constant (Dk), and electrical breakdown strength (E_b) pose significant challenges. Herein, we present the development of all-organic films composed of poly(m-phenylene isophthalamide) (PMIA) and benzo[ghi]perylene (BzP). BzP, serving as a molecular “glue”, interacts with adjacent PMIA chains via π–π stacking, facilitating the formation of hydrogen bonds among PMIA chains. This tailors the long-range disordered chain packing of PMIA into a short-range ordered state, yielding a denser polymer structure that enhances both Dk and E_b. Due to its negative electrostatic potential, BzP acts as an electron scattering center, while a high energy barrier at the PMIA/BzP interface assists in shortening the mean free path of carriers. Hence, high-temperature leakage current is largely suppressed by increasing the effective trap density. By optimizing Dk, E_b, and leakage current, the 0.10 wt% film achieves a U₉₀ (discharge density at efficiency exceeding 90%) of 6.46 J cm⁻³ and a maximum discharge density of 12.50 J cm⁻³ at 150 °C. Even at 200 °C, it retains a U₉₀ of 3.15 J cm⁻³. Furthermore, its robust high-temperature storage modulus, reproducibility, and reliability offer promising potential for future applications.