Optimizing Energy Storage Performance in Polymer Dielectrics through Dual Strategies: Constructing “Peaked” Barrieras and Enhancing Carrier Scattering

Dielectric capacitors play a pivotal role in the advancement of electric power systems and emerging energy technologies. However, the deterioration of dielectric performance in energy storage materials at elevated temperatures represents a significant challenge. In this study, organic electron-scattering agents into polyetherimide (PEI) are introduced, creating a “peaked barrier” to impede charge carrier transport. By doping PEI with an ultralow volume fraction (0.8%) of the organic molecule filler 4-(dimethylamino)phenylboronic acid (4-NB), the electron-repelling nature of 4-NB is leveraged in order to regulate charge carrier injection and transport in a synergistic manner. Consequently, the discharged energy density of the PEI composite material increases to 7.93 J cm⁻³ (720 kV mm⁻¹) at 30 °C. At 150 °C, the discharged energy density increases to 5.21 J cm⁻³ (580 kV mm⁻¹). In both cases, the charge and discharge efficiencies are maintained at 90%. It is noteworthy that the prepared PEI composite material also exhibits excellent charge dissipation characteristics, maintaining stable charge and discharge efficiency even after 50 000 charge–discharge cycles. In summary, the study's design concept systematically optimizes the processes of charge carrier injection, transport, and dissipation. This approach offers a novel perspective for the development of dielectrics that are suitable for long-term energy storage.