Polymer Capacitor Dielectrics for High Temperature Applications

Abstract

Much effort has been invested for nearly five decades to identify and develop new polymer capacitor dielectrics for higher than ambient temperature applications. Simultaneous demands of processability, dielectric permittivity, thermal conductivity, and dielectric breakdown strength dictated by increasing high power performance criteria limit the number of available materials. The present review first explains the advantages of metallized polymer film capacitors over the film-foil, ceramic, and electrolytic counterparts and then presents a comprehensive review on both past developmental effort of commercial resins and recent research progress on new polymers targeted for operating temperature above 150 °C. Some historical background and discussion on the limitation of the commercially available polymer film dielectrics for high temperature applications are also given. In many cases, further development of promising polymers that appear to possess all or most of the important criteria is limited by lack of large scale market incentives but could be of great value to niche applications in the military or aerospace realm.

Crosslinked fluoropolymers exhibiting superior high-temperature energy density and charge–discharge efficiency

“…[3][4][5] Consequently, while polymer dielectrics are the preferred materials for energy storage capacitors owing to their high breakdown strength and low loss, [6][7][8][9][10][11][12][13][14][15][16] their performance typically optimized for operation at ambient temperature declines significantly with the increase of working temperatures. [17][18][19][20] For example, the discharge efficiency (η, η = U e /U o × 100%, U e : discharged energy density, U o : stored energy density) of biaxially oriented polypropylene (BOPP) films, which is the best commercially available dielectric polymer, decreases steeply from 96.2% to 87.4% and 68.5% with increasing temperature from 25 o C to 80 o C and 120 o C, respectively, at an applied field of 400 MV m -1 . On the other hand, the rapidly evolving electrification of transportation demands electric power systems to be located in or near engines possessing high temperatures.…”

“…On the other hand, the rapidly evolving electrification of transportation demands electric power systems to be located in or near engines possessing high temperatures. [19][20][21] For instance, polymer capacitors are essential components of power inverters in electric vehicles, where the working temperature is around 150 °C. Wide bandgap semiconductors, e.g.…”

Ternary polymer nanocomposites with concurrently enhanced dielectric constant and breakdown strength for high‐temperature electrostatic capacitors

“…Recently, engineering polymers with high glass transition temperature (T g ), such as polycarbonate, polyimide (PI), poly(arylene ether nitrile), and poly(ether ketone ketone) have been exploited as high-temperature dielectric materials. 14,[17][18][19][20][21][22][23] Unfortunately, all the polymers suffer considerable energy loss under high electric fields and at elevated temperatures, which is due to the leakage current that increases exponentially with increasing temperature, resulting in sharp drops in both energy density and chargedischarge efficiency of the polymer dielectrics.…”

Revealing the correlation between molecular structure and dielectric properties of carbonyl‐containing polyimide dielectrics

“…[9][10][11] However, the dissipation factor would increase largely when temperature is above 85 C, and the dielectric constant is expected to be enhanced in further in order to obtain larger maximum energy storage density. 13,14 Ferroelectric polymers such as poly(vinylidene) fluoride (PVDF) and its random copolymers P(VDF-TrFE) and P(VDF-TrFE-CFE) (TrFE: trifluoroethylene; CFE: chlorofluoroethylene) are of high dielectric constant; however, besides the relatively high dissipation factor, the low curie temperature (about room temperature) and melting points (<170 C) limit their high-temperature applications. 13,14 Ferroelectric polymers such as poly(vinylidene) fluoride (PVDF) and its random copolymers P(VDF-TrFE) and P(VDF-TrFE-CFE) (TrFE: trifluoroethylene; CFE: chlorofluoroethylene) are of high dielectric constant; however, besides the relatively high dissipation factor, the low curie temperature (about room temperature) and melting points (<170 C) limit their high-temperature applications.…”

“…12 Therefore, for the purpose of meeting the requirement of high-temperature capacitors in hostile circumstances, it is of great importance to develop high-temperature resistant polymer dielectrics with superior dielectric properties. 13,14 Ferroelectric polymers such as poly(vinylidene) fluoride (PVDF) and its random copolymers P(VDF-TrFE) and P(VDF-TrFE-CFE) (TrFE: trifluoroethylene; CFE: chlorofluoroethylene) are of high dielectric constant; however, besides the relatively high dissipation factor, the low curie temperature (about room temperature) and melting points (<170 C) limit their high-temperature applications. [15][16][17] On the other hand, polar polymers such as polyurea and polyurethane, polythoiurea, poly(phenyl oxide), polyimide with reasonably increased dielectric constant and acceptable dissipation factor have been studied by many research groups.…”