Superior Energy Storage Performance in Antiferroelectric Epitaxial Thin Films via Structural Heterogeneity and Orientation Control

Abstract Dielectric capacitors are desired for electronics and electrical power systems because of their fast charge–discharge speed and high‐power density. Nevertheless, dielectric capacitors typically exhibit lower energy densities in comparison to other energy storage systems like batteries or fuel cells. Among dielectrics, antiferroelectrics have shown great promise for high energy density because of their characteristic double hysteresis loops. However, current antiferroelectric capacitors still face challenges of low efficiency and low breakdown strength due to their large hysteresis, which is harmful to energy efficiency and reliability of the system. Herein, by engineering the nanoscale heterogeneity to mitigate hysteresis and controlling orientation to enhance the polarization, the exceptional energy storage performance of antiferroelectric (Pb 0.97 La 0.02 )(Zr 0.55 Sn 0.45 )O 3 epitaxial thin films is demonstrated. Atomic‐resolution transmission electron microscopy and X‐ray reciprocal space mapping confirm the presence of nanoscale structural heterogeneity, characterized by fragmented antipolar nanodomains. These films exhibit remarkable energy densities, reaching up to ≈84.5 J cm −3 , coupled with ultrahigh efficiencies of up to ≈98.5% and superior stability, maintaining efficiencies above 92% across a wide field range of ≈5 MV cm −1 . Notably, these findings surpass the capabilities of previously reported dielectric materials, opening new avenues for advanced energy storage applications.