Polar-fluoropolymer blends with tailored nanostructures for high energy density low loss capacitor applications

A polar-fluoropolymer blend consisting of a high energy density poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) and a low dielectric loss poly(ethylene-chlorotrifluoroethylene) (ECTFE) was developed. Both the blend and crosslinked blend films exhibit a dielectric constant of 7 and low loss (∼1%), as expected from the classical composite theory. Moreover, introducing crosslinking in the blends can lead to a marked reduction of losses in blend films at high fields while maintaining a high energy density. At 250 MV/m, a loss of 3% can be achieved in the crosslinked blend compared with 7% loss in pure blend, which is already much below that of neat P(VDF-CTFE) (∼35%).