Extraordinary energy storage performance and thermal stability in sodium niobate-based ceramics modified by the ion disorder and stabilized antiferroelectric orthorhombic R phase

Developing high-performance dielectric capacitors is essential to meet the growing demands of hybrid electric vehicles and high-power applications. The energy storage efficiency and the temperature-variant energy storage properties should be considered besides the energy density. In this work, we prepared (1 −x)(0.8NaNbO₃-0.2SrTiO₃) −xBi(Zn_0.5Sn_0.5)O₃(abbreviated as (1 −x)(NN-ST) −xBZS) lead-free ceramics, where ion disorder is induced in the A-B sites. The experimental results indicate that the antiferroelectric orthorhombic R phase is stabilized, and the breakdown strength is enhanced due to the decreased grain size after BZS modification, which are conducive to optimizing the energy storage performance. The piezoresponse force microscopy (PFM) observation reveals that the incorporated BZS promotes the reversibility of domains, resulting in enhanced energy storage efficiency. Therefore, an energy density of 5.82 J cm⁻³and an efficiency of 92.3% are simultaneously obtained in the 0.96(NN-ST) − 0.04BZS composition, and the obtained efficiency in this work reaches a record high in NN-based energy storage ceramics. Especially, the sample displays extraordinary temperature stability, that is, high energy storage density (3.6-4.31 J cm⁻³) and efficiency (90-95%) are achieved in a wide temperature range from −60 °C to 180 °C. Our work would provide a powerful strategy for designing high-performance energy storage capacitors operating in harsh environments.