Novel polar-fluoropolymer blends with tailored nanostructures for high energy density and low loss capacitor applications

Dielectric polymers with high energy density with low loss at high electric fields are highly desired for many energy storage and regulation applications. A polar-fluoropolymer blend consisting of a high energy density polar-fluoropolymer of poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) with a low dielectric loss polymer of poly(ethylene- chlorotrifluoroethylene) (ECTFE) was developed and investigated. We show that the two polymers are partially miscible which leads to blends with high energy density and low loss. Moreover, by introducing crosslinking to further tailor the nano-structures of the blends a markedly reduction of losses in the blend films at high field can be achieved. The crosslinked blend films show a dielectric constant of 7 with a dielectric loss of 1% at low field. Furthermore, the blends maintain a high energy density and low loss (∼3%) at high electric fields (> 250 MV/m).