Superior energy storage performance in (Bi0.5Na0.5)TiO3-based lead-free relaxor ferroelectrics for dielectric capacitor application via multiscale optimization design

Abstract

Developing environmentally friendly lead-free dielectric ceramics with ultrahigh energy storage performance is fundamental to next-generation high-power capacitors but challenging as well. Herein, a record-breaking ultrahigh energy efficiency η of 97.8% and high energy density W_rec of 5.81 J cm⁻³ are simultaneously achieved in (Bi_0.5Na_0.5)TiO₃ (BNT)-based relaxor ferroelectric ceramics by introducing linear dielectric CaTiO₃ in order to synergistically manipulate the domain structure and microstructure evolution at the multiscale, generating the existence of stable and highly-dynamic polar nanoregions, fine grain size, suppressed leakage current density, and a large band gap E_g concurrently. More excitingly, the designed ceramic shows a remarkable thermal endurance (W_rec ≈ 3.7 ± 0.2 J cm⁻³, η ≈ 96% ± 3%, 30–160 °C), frequency stability (W_rec ≈ 3.9 ± 0.2 J cm⁻³, η ≈ 98% ± 2%, 5–200 Hz), cycling reliability (W_rec ≈ 3.5 ± 0.1 J cm⁻³, η ≈ 95% ± 2%, 1–10⁵ cycles) at 350 kV cm⁻¹, and superior discharge performance (power density P_D ≈ 96.2 MW cm⁻³, discharge speed t_0.9 ≈ 37.6 ns). This study explores high performance lead-free relaxor ferroelectrics for energy storage capacitors and offers an effective strategy to tailor the dielectric of relaxor ferroelectrics.