Sandwich structure strategy for constructing BiFeO3-based film capacitor with high energy storage performance

Lead-free dielectric capacitors have been garnering increasing attention for pulsed power applications owing to their green sustainability. BiFeO 3 (BFO) is widely researched in association with dielectric energy-storage applications, owing to its large saturated polarization and high Curie temperature. However, it suffers from serious leakage problems. In this work, BFO-based thin films with different stacking structures are designed and fabricated by introducing a linear dielectric material, SrTiO 3 (STO). The experimental results and finite-element simulations indicate that the polarization and breakdown strength can be simultaneously optimized by regulating the position of the STO layer. In particular, a recoverable energy density of 70 J/cm 3 and efficiency of 60 % is achieved in sandwiched Bi(Fe 0.93 Mn 0.05 Ti 0.02 )O 3 /SrTiO 3 /Bi(Fe 0.93 Mn 0.05 Ti 0.02 )O 3 (BFMTO/STO/BFMTO) film, owing to the synergistic effect of different dielectrics as well as the blocking effect of the interface. The capacitor exhibits a wide operating temperature window (-100–125 °C) and high frequency stability (1–20 kHz), as well as strong fatigue durability (2 × 10 7 cycles). These results demonstrate that the BFMTO/STO/BFMTO film is a promising ecofriendly material for advanced power-capacitor applications.