Improvement of Energy Storage Properties of NaNbO3-Based Ceramics through a Relaxation Strategy

Abstract

NaNbO3 (NN) is a widely studied antiferroelectric ceramics in recent years. However, NN ceramics always exhibit a square P-E loop with larger P r, originating form an irreversible antiferroelectric-ferroelectric (AFE-FE) phase transition under an applied electric field and limit the further development. In this paper, a novel lead-free relaxor ferroelectric ceramic, (1−x)NaNbO3-x(0.5Bi0.5Na0.5TiO3−0.5Ba0.3Sr0.7TiO3) [(1−x)NN-xBNBST, x = 0, 0.10, 0.15, 0.20, 0.25, 0.30], was designed and prepared via a local random field relaxation strategy. Dielectric testing show that the addition of BNBST significantly improved the relaxor behavior of the NN, which is effective for enhancing the W rec and η of NN-based ceramics. When x = 0.2, the ceramic obtains a high recoverable energy storage density (W rec = 2.024 J cm−3) and energy storage efficiency (η = 63%) at a low electric field of 130 kV cm−1. Meanwhile, the polarization-electric field (P-E) hysteresis loops and charge-discharge results of the sample with x = 0.2 at different temperatures and frequencies show that it is a prospective material for pulsed energy storage capacitors.