2–2 Type PVDF‐Based Composites Interlayered by Epitaxial (111)‐Oriented BTO Films for High Energy Storage Density

Abstract Quick charge/discharge polymer‐based composites filled with inorganic nanosheets have attracted extensive attention and provided a more efficient way to achieve high energy storage density ( U ) because of the alleviated agglomeration of fillers and the formation of conduction barriers. However, conductive paths have a chance to extend along out‐of‐plane directions by circumventing the micrometer‐sized nanosheets. Here, large‐sized (111)‐oriented BaTiO 3 (BTO) films with outstanding epitaxiality and ferroelectricity are embedded in poly(vinylidene fluoride) (PVDF) using optimal transfer and hot‐pressing processes. The 2D–2D (2–2) type BTO/PVDF composites interlayered by 2‐layer BTO (about 0.2 µm thick of each layer) exhibit the highest U of 20.7 J cm ‐3 at 690 MV m ‐1 , which is 222.6% that of pure PVDF. Phase‐field simulations reveal that high‐resistance PVDF films as outer layers can prevent the charges injection from electrodes and high‐dielectric BTO films as inner layers can effectively suppress the mobile charges across interfaces between layers, leading to a remarkable improvement of breakdown strength. This work puts forward a scalable approach to enhance the U of inorganic/organic composites for advanced energy storage materials and applications.