742 / 2022-03-31 20:26:24

Improved energy storage of polyetherimide / PCBM composites with excellent discharge efficiency

energy storage,discharge efficiency,polyetherimide / PCBM composites

Purpose/Aim

Polymer dielectrics have been widely used in capacitors due to their excellent advantages such as high breakdown strength, ease of film forming and low cost. However, they still suffer from low energy density and poor discharge efficiency, which limits their use in high electric field. In this work, the polyetherimide / PCBM composites was synthesized to improve the energy storage performance.

Experimental/Modeling methods

The polyetherimide / PCBM composite films were prepared by solution casting method. For study the chemical bonds and molecular structure, the FTIR analysis was performed. The morphology and distribution of PCBM was observed through SEM. The dielectric property of the composite materials was measured in the frequency band of 0.1 to 10⁶ Hz. The energy storage and discharge efficiency were acquired by the displacement-electric field (D-E) loops. The trap energy level was estimated by TSDC.

Results/discussion

Due to its high electron affinities, PCBM can introduce a trap with energy level of 1.5eV in the composites, which significantly hindered the charge transportation and suppressed the leakage current. Incorporated with 0.50 vol.% of PCBM, the composites achieved a high discharged energy density of 5.4 J/cm³ with 90% efficiency, which is 15% higher than undoped polyetherimide and much higher than the commercial capacitor dielectric biaxially oriented polypropylene with ~3.5 J/cm³.

Conclusions

Introduced with very low concentrations of PCBM, the composites achieved an improved energy storage and excellent discharge efficiency. The vastly improved energy density could help reduce the capacitor size and enable compact power modules.