Breakdown strength improvement of polypropylene by introducing long-chain branched structures for film capacitors

In this paper, maleic anhydride (MAH) was grafted on the surfaces of biaxially oriented polypropylene (BOPP) film by ultraviolet irradiation treatment to improve the breakdown strength. The addition of MAH, with abundant deep traps, effectively hinders charge injection from the electrode, leading to improved dielectric performance, particularly at elevated temperatures. The experimental results show that the received modified film exhibits an improved permittivity of 2.37 alongside a low dielectric loss of 0.0022 at 1000Hz. Remarkably, the DC breakdown strength reaches 633.9 kV/mm, marking a notable 21.4% increase compared to the unmodified BOPP film at 120 °C. Moreover, the film exhibits an energy density of 2.58J/m³, which is 1.59 times that of the pure film. The charging and discharging efficiency is also greatly improved due to the reduction of conductance losses . Through simulation results, it becomes evident that the enhanced performance is attributed to the alleviation of electric field distortion due to the suppression of injected charge. This work paves a facile route to design scalable polymeric dielectrics with outstanding performance, which facilitates the development of ﬁlm capacitors.

Section: Discussionmentioning

confidence: 99%

Enhanced energy density of BOPP film by MAH grafting for metallized capacitors

Chen,

Du,

Liu

et al. 2024

“…Thus, the restricted displacement of molecular chains further decreased the influence of temperature in aggregated structure, so the energy storage properties of ternary nanocomposites have the better temperature stability. The enhancement of molecular chain entanglement and the large number of deep traps were the main reasons for the higher BDS of PP/50AA/0.5Zr ternary nanocomposites at elevated temperatures [29].…”

Section: Mechanism Of Energy Storage Improvementmentioning

confidence: 96%

Enhanced energy storage performance in polypropylene-acrylic acid grafted polypropylene-ZrO₂ ternary nanocomposites

Liu¹,

Liu²,

Liu³

et al. 2023

To improve the energy storage density while maintaining low dielectric loss is crucial for the miniaturization of capacitors. In the present study, we proposed a ternary nanocomposite system comprised of polypropylene (PP), acrylic acid grafted polypropylene (PP-g-AA), and nano-ZrO2. The PP-g-AA was firstly prepared by a free radical grafting with the proportion fixed to 50 wt%, and the content of nano-ZrO2 ranged from 0.5 wt% to 5 wt% to tailor the ternary composite. The transmission electron microscope (TEM) observation showed that PP-g-AA could significantly benefit the dispersion of nanoparticles and the differential scanning calorimetry (DSC) results indicated the superior compatibility of the ternary nanocomposites. Accordingly, with the optimum nano-ZrO2 content of 0.5 wt%, the ternary nanocomposites achieved the permittivity of 2.7 and DC breakdown strength of 456.2 kV/mm, resulting in the enhanced energy density of 2.77 J/cm3 which was 60% higher than neat PP, while the dielectric loss was kept lower than 0.003. Moreover, even at the temperature of 120°C, the ternary nanocomposites maintained a high-performance energy storage density of 2.28 J/cm3 (with energy storage efficiency above 90%) , which was 670% of the neat PP.

“…With the development of new power systems, capacitors as the core equipment to realize AC/DC power conversion have gradually developed [1][2][3], among which the metallized film capacitors (MFCs) are widely used due to their advantages of high energy density and long service life [4,5]. Polypropylene (PP) enjoys the reputation as the most commercialized dielectric material for MFCs because of its high breakdown strength and low dielectric loss [6][7][8]. However, the temperature and electric field strength of the working environment constantly rise with the expanding installed scale and capacity of power * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Dielectric performance improvement of polypropylene film by hierarchical structure design for metallized film capacitors

Xiao,

Zhang,

2024

Self Cite

In this paper, hierarchical structure design method is proposed for improving the dielectric performance of polypropylene (PP) for metallized film capacitors. The results show that the composite film with 0.02 wt% terephthalaldehyde doping and functional layer thickness occupying 25% shows the best dielectric properties. The leakage conductivity declines by 89.0%–94.3%, the DC breakdown strength grows by 15.6%–19.7% and the discharged energy density improves by 50.6%–53.4%. Terephthalaldehyde doping introduces sites that could capture free holes, thereby blocking the carrier migration path. The hierarchical structure design results in the holes accumulating in the functional layer and the reverse electric field formed suppresses the charge injection from the anode. Furthermore, the probability of intrinsic charge excitation due to the band gap width reduction is greatly reduced. The method provides a reference for improving the dielectric performance of PP films from the perspective of regulating the charge transmission behavior.