Excellent thermal stability and energy storage properties of lead‐free Bi0.5Na0.5TiO3‐based ceramic

The ceramic capacitors with excellent energy storage properties and wide operating temperature are the main challenges in power system applications. Here, the lead‐free (1‐x)Bi0.5Na0.5TiO3‐xCaTiO3 (abbreviated as BNT‐xCT) ceramics were synthesized through solid‐state reaction method. The introduction of CT reduced the temperature of permittivity peak of BNT ceramic, guaranteeing excellent thermal stability over a wide temperature range of −100 ∼ 136°C. Meanwhile, the long‐range order structure of BNT was destructed by structural distortion, and the relaxor behavior was enhanced after doping CT. Moreover, the direct current breakdown strength was improved from 203 to 455 kV/cm, and the high recoverable energy density (Wrec ∼ 2.74 J/cm3) with high efficiency (η ∼ 91%) was achieved for BNT‐0.25CT ceramic, along with a fast discharge speed (t0.9 ∼ 110 ns) superior cycle stability and thermal stability. Those properties enabled a promising practical prospect of BNT‐CT ceramics.