Enhanced energy storage performance and thermal stability in relaxor ferroelectric (1‐x)BiFeO 3 ‐x(0.85BaTiO 3 ‐0.15Bi(Sn 0.5 Zn 0.5 )O 3 ) ceramics

Lead‐free (1‐ x )BiFeO 3 ‐ x (0.85BaTiO 3 ‐0.15Bi(Sn 0.5 Zn 0.5 )O 3 ) [(1‐ x )BF‐ x (BT‐BSZ), x =0.45‐0.7] ceramic samples were prepared by solid phase sintering. It is revealed that the pure single‐phase perovskite structure can be obtained in samples with x ≥ 0.6. With increasing x , the measured ferroelectric hysteresis loop becomes gradually slimmed in accompanying with reduced remnant polarization, and a clear ferroelectric‐relaxor transition at x = 0.65 is identified. Furthermore, the measured electric breakdown strength can be significantly enhanced with increasing x , and the optimal energy storage performance is achieved at x = 0.65, characterized by the recoverable energy storage density up to ≈3.06 J/cm 3 and energy storage efficiency as high as ≈92 %. Excellent temperature stability (25°C–110°C) and fatigue endurance (>10 5 cycles) for energy storage are demonstrated. Our results suggest that the BF‐based relaxor ceramics can be tailored for promising applications in high energy storage devices.