Enhanced energy storage properties of lead-free NaNbO3-based ceramics via A/B-site substitution

Lead-free ceramic-based dielectric capacitors have attracted extensive investigation due to their potential applications in pulsed power devices. However, the main drawback of dielectric ceramics is the relatively low energy storage density. Herein, Bi3+ and Mg2+ with different ionic radius and valence are introduced into antiferroelectric NaNbO3 matrix to form (Na1-3/2xBi3/2x)(Nb1-xMgx)O3 solid solutions, where the antiferroelectric phase is stabilized and the relaxor behavior is also improved. Of particular importance is that a large breakdown strength (Eb) of 78.3 kV/mm, an ultrahigh recoverable energy density (Wrec) of 10.9 J/cm3 and efficiency (eta) of 83% are simultaneously achieved in (Na0.91Bi0.09)(Nb0.94Mg0.06)O3 ceramic. Moreover, the energy storage properties of (Na0.91Bi0.09)(Nb0.94Mg0.06)O3 ceramic also reveals superior frequency (1-100 Hz), cycling (100-105) and thermal (30 degrees C-100 degrees C) stability, together with the ultrafast discharge rate (<25 ns). These results demonstrate the NaNbO3-based lead-free relaxor antiferroelectric ceramics is a promising candidate for energy storage application.