High Energy Storage Performance and Large Electrocaloric Response in Bi0.5Na0.5TiO3–Ba(Zr0.2Ti0.8)O3 Thin Films

With regard to the global energy crisis and environmental pollution, ferroelectric thin films with unique polarization behavior have garnered considerable attention for energy storage and electrocaloric refrigeration. Herein, a series of (1 – x )Bi 0.5 Na 0.5 TiO 3 – x Ba(Zr 0.2 Ti 0.8 )O 3 ( x = 0.3–0.9; (1 – x )BNT– x BZT) films were fabricated on Pt(111)/Ti/SiO 2 /Si substrates. Incorporating BZT can tune the polarization behavior and phase transition temperature of BNT. A high recoverable energy density ≈ 82 J cm –3 and optimized efficiency ≈ 81% were realized for the (1 – x )BNT– x BZT thin film with x = 0.7. The thin film exhibits excellent stability in energy storage performance, a wide working frequency range (0.5–20 kHz), a broad operating temperature window (20–200 °C), and reduplicative switching cycles (10 7 cycles). In addition, the 0.5BNT–0.5BZT film exhibits a desirable electrocaloric effect with a large adiabatic temperature change (Δ T ≈ −22.9 K) and isothermal entropy change (Δ S ≈ 33.4 J K –1 kg –1 ) near room temperature under a moderate applied electric field of 2319 kV cm –1 . These remarkable performances signify that the (1 – x )BNT– x BZT system is a promising multifunctional electronic material for energy storage and solid-state cooling applications.