Fatigue resistant lead-free multilayer ceramic capacitors with ultrahigh energy density

Abstract

The critical role of electrical homogeneity in optimising electric-field breakdown strength (BDS) and energy storage in high energy density (0.7 − x)BiFeO₃–0.3BaTiO₃–xBi(Li_0.5Nb_0.5)O₃ (BF–BT–xBLN) lead-free capacitors is demonstrated. The high BDS for bulk ceramics and multilayers (dielectric layer thickness ∼ 8 μm) of ∼260 and ∼950 kV cm⁻¹, respectively, gives rise to record-performance of recoverable energy density, W_rec = 13.8 J cm⁻³ and efficiency, η = 81%. Under an electric field of 400 kV cm⁻¹, multilayers are temperature stable up to 100 °C, frequency independent in the range 10⁻² to 10² Hz, have low strain (<0.03%) and are fatigue-resistant up to 10⁴ cycles (W_rec variation < 10%). These properties show promise for practical use in pulsed power systems.