Largely Improved Breakdown Strength and Discharge Efficiency of Layer‐Structured Nanocomposites by Filling with a Small Loading Fraction of 2D Zirconium Phosphate Nanosheets

Abstract Dielectric film capacitors have aroused considerable attention on account of the fast development of pulsed power systems. However, enhanced energy density is always acquired at the cost of deteriorated charge/discharge efficiency. Herein, well balanced energy density and efficiency are achieved in a series of reasonably designed bilayer composites consisting of a ferroelectric layer and a paraelectric layer at the meantime. It is interesting to find that, when merely 1.6 wt% Zr(HPO 4 ) 2 nanosheets are introduced into the ferroelectric layer, a substantially improved energy density of 11.22 J cm −3 , which is about 165% that of the bilayer composite without Zr(HPO 4 ) 2 nanosheets, is achieved at 650 kV mm −1 . Meanwhile, a high charge/discharge efficiency of 89.8% and a low loss tangent of 0.024@10 kHz which is much lower than the pristine ferroelectric polymer layer (0.058@10 kHz) is maintained. Furthermore, finite element simulation reveals that the electric breakdown paths will develop along the macroscopical‐interfaces between adjoining layers and the microcosmic‐interfaces between the Zr(HPO 4 ) 2 nanosheets and polymer matrix, which can effectively increase the length of breakdown paths and contribute to improved breakdown strength. This work demonstrates that the Zr(HPO 4 ) 2 nanosheets can be promising fillers for other high‐performance dielectric composites.