Improved Working Temperature and Capacitive Energy Density of Biaxially Oriented Polypropylene Films with Alumina Coating Layers

Abstract

High-temperature dielectric energy-storage properties are crucial for polymer-based capacitors for harsh environment applications. However, biaxially oriented polypropylene (BOPP), a state-of-the-art commercial capacitor dielectric, can work only below 105 °C. Here, we present a versatile method to enhance its working temperature by depositing alumina (Al2O3) layers onto BOPP films via magnetron sputtering. Compared with a pure BOPP film, the sandwiched Al2O3/BOPP/Al2O3 structure shows a higher dielectric constant, a lower electrical conduction loss, stronger mechanical properties, higher thermal conductivity, and especially increased working temperature. As a result, the composite film delivers a high discharged energy density of 0.45 J/cm3 under 200 MV/m (the actual operating electric field in hybrid electric vehicles) at 125 °C. The discharged energy density and energy-storage efficiency (∼97.7%) are highly stable over 5000 cycles at 125 °C. This work provides an effective route to develop high-temperature polymer-based capacitors.

Significant improvement in high-temperature energy storage performance of polymer dielectrics via constructing a surface polymer carrier trap layer

“…So far, the BOPP-F film in this work outperforms current PP-based modified polymers in terms of U e at room and high temperatures. 29,37–43…”

“…So far, the BOPP-F lm in this work outperforms current PP-based modied polymers in terms of U e at room and high temperatures. 29,[37][38][39][40][41][42][43] In addition to energy storage and charge-discharge efficiency, the charge-discharge cycling performance is another key point for the long-term application of capacitors. For an assessment of their fatigue resistance, BOPP-FS and BOPP-F were taken as representative surface-functionalized samples for cyclic charging-discharging tests, and the results are compared with those of the pristine BOPP lm in Fig.…”

Modulating the charge trapping characteristics of PEI/BNNPs dilute nanocomposite for improved high-temperature energy storage performance

“…S8, ESI †). 3,7,8,11,17,21,28,32,33,40,44,45,[47][48][49][50][51] In the fields of practical application, the stability and reliability of the dielectrics are also critical factors to be considered. To verify the reliability of the dilute nanocomposite film, cycling and the rapid charge-discharge tests were performed on the nanocomposite film with 0.25 Vol% filler loading at 150 1C and 300 MV m À1 (Fig.…”

“…12,[23][24][25][26][27] One effective approach to reducing the leakage current is to impede the charge injection from the electrode into the dielectric materials, which has been realized by adding a high insulative layer between the polymer surface and metal electrodes. 5,9,21,[27][28][29] For instance, growing the SiO 2 layer on the surface of PEI film can create an effective electron barrier at the interface between the electrode and the dielectric, which blocks the charge injection and thus reduces the leakage conductance. 29 Another method is to introduce the fillers with wide band gaps, which can effectively hinder charge injection or excitation, thereby avoiding the avalanche growth of secondary ionized electrons.…”

Biodegradable Poly(l-Lactic Acid) Films with Excellent Cycle Stability and High Dielectric Energy Storage Performance

“…Most recently, Yang et al constructed an amorphous polylactic acid (PLA)-based organic–inorganic composite film with a largely improved dielectric constant of ∼7.9, delivering an enhanced energy storage density of 1.7 J/cm 3 under 200 MV/m at room temperature, which is 240% higher than that of BOPP (<0.5 J/cm 3 ). , However, the inferior charge–discharge efficiency (η) of 83% and low breakdown strength (below 300 MV/m) of amorphous PLA composite films are detrimental to practical applications. The crystallized PLLA film should exhibit improved energy storage performance for the following reasons: (1) The heat resistance of PLLA has been demonstrated to increase with the crystallinity degree.…”