Rational Design of Soluble Polyaramid for High‐Efficiency Energy Storage Dielectric Materials at Elevated Temperatures

Abstract

High‐temperature polymer dielectrics are in great demand for harsh‐environment applications. Maintaining high‐energy storage density and low loss at elevated temperatures remains a major challenge for polymer dielectrics. In this work, a new type of polymer dielectric material is designed, which exhibits comparable dielectric properties in the start‐of‐the‐art dielectric nanocomposites and a superior potential for scale up. A soluble, glassy state polymer with a polarizing group is designed by introducing a weakly polar group into the polyaramid (PA) backbone to dilute the hydrogen bonding of the PA parent species. This increases the mobility of the molecular dipole within the polymer in the glassy state, thereby increasing its dielectric constant while maintaining the high‐temperature performance. The result of this design is a polymer with a glass transition temperature of 251 °C, a dielectric constant of up to 4.5, and a dielectric loss of 1%, while maintaining 2.1 J cm−3 energy density and 86.8% efficiency at 200 °C. This polymer, with its excellent, intrinsic, electrical‐energy‐storage properties can also be adapted for a roll‐to‐roll capacitor film production. Breaking intermolecular hydrogen bonds to enhance the electrical‐energy‐storage properties of polymers is an excellent path for designing polymer dielectrics with high‐temperature capabilities.

Dielectric polymers for high-temperature capacitive energy storage

“…Recently, another flexible linkage -ether ketone was introduced into the aromatic polyamide (PA) backbone to afford soluble poly(naphthalene ether ketone amide) (PEKNA). 140 This is to address the issue that PAs are notoriously difficult to be processed into highquality thin films because of their rigid main chain structure and high density of interchain hydrogen bond. Specifically, as shown in Fig.…”

Research Progress of All Organic Polymer Dielectrics for Energy Storage from the Classification of Organic Structures

“…Xu et al. [ 108 ] obtained a poly(naphthalene ether ketone amide) (PEKNA) via Yamazaki phosphorylation polymerization. They revealed that the mobility of molecular dipoles could be enhanced by introducing a weakly polar group into the main chain of PA to weaken the hydrogen bonds between the amides.…”

“…[ 113 ] A relatively high discharge energy density of 1.5 J cm −3 can be achieved for PEI even at a high temperature of 150 °C, which is about twice higher than that of PI. [ 108 ] More recently, Tuncer et al. [ 114 ] investigated the non‐parametric dielectric response of the PEI via a numerical inversion algorithm to solve the relaxation time distribution of the PEI films with a thickness of 5 µm.…”

2D MoS2 Nanosheet‐Based Polyimide Nanocomposite with High Energy Density for High Temperature Capacitor Applications

“…The charge-discharging efficiency of the PEKNA material reached 86.8% at 200°C. [29] Ren et al reported a nanocomposite consisting of a PEI substrate with hafnium oxide (HfO 2 ) nanoparticles to achieve an energy density of 2.82 J cm −3 at 150°C. [30] A hightemperature dielectric energy storage material was prepared by adding montmorillonite (MMT) nanosheets to the PAI polymer, which exhibited an energy density of 3.6 J cm −3 at a temperature of 150°C.…”

“…The charge–discharging efficiency of the PEKNA material reached 86.8% at 200 °C. [ 29 ] Ren et al. reported a nanocomposite consisting of a PEI substrate with hafnium oxide (HfO 2 ) nanoparticles to achieve an energy density of 2.82 J cm −3 at 150 °C.…”