Extended Data Fig. 1: Schematic of dielectric energy storage.

a, P-E loops in response to the application and removal of an unipolar electric field. The recoverable energy density (the grey area) is written as \({U}_{\text{d}}={\int }_{{P}_{\text{r}}}^{{P}_{\text{m}}}{EdP}\), where P_m and P_r are indicated. The efficiency is defined as η = U_d/(U_d+U_loss). The dashed arrows indicate the application and removal of an applied electric field corresponding to charge and discharge processes, respectively. b, Sketch of P-E loops in normal ferroelectrics. c, Intrinsic versus extrinsic ε_eff with respect to electric field. Intrinsic ε_eff is always smaller than ε_r in ferroelectrics regardless of normal ferroelectric or relaxor ferroelectrics (solid lines). Extrinsic ε_eff can markedly exceed ε_r (dashed lines). d, Sketch of dielectric relaxation occurring in relaxor ferroelectrics under different temperatures and frequencies (upper panel). Energy storage at different temperatures (bottom panel). Schematic of the all-trans and 3/1-helix conformation. e, All-trans. f, 3/1-helix. The arrows indicate the projections of the directions of -CF₂- dipole on planes defined by the carbon backbone. g, Sketch of track of -CF₂- dipole rotation in the 3/1-helical conformation. MPB phase in the main text refers to the coexistence of the all-trans and 3/1-helix conformations with flat energy landscape.