Fig. 1.

Breakdown evolution and corresponding energy density distributions. The breakdown evolution processes of poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) polymer predicted by the extended phase-field model at different applied electric fields and temperatures of a–c 295 K, d–f 323 K, and g–i 363 K. The applied field $E_y^{\mathrm{app}}$ is along the y direction and is shown by the red arrow in a. The initial breakdown phase is nucleated from the two needle electrodes. j–r show the electric energy density f_elec, Joule heat energy density f_Joule, and strain energy density f_strain for the breakdown states of c, f, and i