MEETING : Multilayer Polymer Dielectric Films for Next Generation Film Capacitors

Advanced dielectric film capacitors have become increasingly important in mobile power electronic systems such as those used in electric vehicles (EVs). Current state-of-the-art biaxially oriented polypropylene (BOPP) films start to face technical issues including low energy density and high conduction loss at temperatures above 85 °C.

At Case Western Reserve University, we have developed a novel multilayer film technology to meet the stringent requirements for next generation dielectric film capacitors in EVs and HEVs. By multilayering a high breakdown strength polymer such as polycarbonate (PC) with a high dielectric constant polymer such as poly(vinylidene fluoride) (PVDF), we have achieved high breakdown strength (>600 MV/m), high energy density at breakdown (16 J/cc), and relatively low dielectric dissipation factor (tan <0.006) and hysteresis loss (15% loop area).

In this presentation, we will identify and discuss the fundamental issues for multilayer capacitor films. 

They include prevention of VDF dipole flipping, reducing migrational loss from impurity ions in PVDF, reducing DC conduction at high temperatures, and utilizing Maxwell-Wagner-Sillars interfacial polarization to achieve enhanced breakdown strength and lifetime.

Professor Lei Zhu received his B.S. degree in Materials Chemistry in 1993 and M.S. degree in Polymer Chemistry and Physics in 1996 from Fudan University.

He received his Ph.D. degree in Polymer Science from University of Akron in 2000. After two-year post-doctoral experience at the Maurice Morton Institute, University of Akron, he joint Institute of Materials Science and Department of Chemical, Materials and Biomolecular Engineering at University of Connecticut, as an assistant professor.

In 2007, he was promoted to associate professor with tenure. In 2009, he moved to Department of Macromolecular Science and Engineering at Case Western Reserve University as an Associate Professor.

In 2013, he was promoted to full Professor. His research interests include high k polymer and organic-inorganic hybrid nanomaterials for high energy density capacitor applications, development of artificial antibody as nanomedicines, and supramolecular self-assembly of discotic liquid crystals. He is recipient of NSF Career Award, 3M Non-tenured Faculty Award, DuPont Young Professor Award, and Rogers Teaching Excellence Award.

He is author and co-author of 121 refereed journal publications and 5 book chapters.

He delivered 108 invited talks and 45 contributed presentations, and his total citation is over 4100 times with an h-index of 35 (Google Scholar).