Achieving Ultrahigh Energy Storage Density in Lead-Free Sodium Niobate-Based Ceramics by Modulating the Antiferroelectric Phase

摘要

Lead-free antiferroelectric ceramics have drawn widespread interest recently on account of their environmentally friendly components and potential applications in high-power systems.However,their relatively low recoverable energy storage density(W_(rec)<10 J/cm~3),limited by the electric breakdown strength(Eb<60 kV/mm),and low efficiency(η<80%),generated by large hysteresis during the antiferroelectric-ferroelectric phase transition,have seriously restricted their application in portable and compact electronic devices.In this study,the relaxor antiferroelectric(1-x) NaNbO_(3-x)(0.55BiFeO3-0.45SrTiO3) ceramics were elaborately designed and systematically explored.With the help of composition regulation,the ceramics not only exhibited a stable antiferroelectric phase but also underwent a structural transformation from an antiferroelectric P {Pbma) phase to R.(Prima) phase,as conhrmed by the temperature-dependent dielectric constants,Raman spectra,X-ray diffraction(XRD) refinement,pinched polarization-electric field(P-E) curves,and four-peak current-electric field(I-E) curves.In addition,the relaxor characteristic was demonstrated by the diffuse dielectric peaks,slim P-E curves,flattened Raman peaks,and I-E curves.Consequently,novel relaxor antiferroelectric ceramics were successfully obtained,which simultaneously revealed the features of relaxor and antiferroelectricity.Specifically,the Eb was significantly improved because of the reduced grain size,small sample thickness,exceptionally low dielectric loss,and a moderate dielectric constant.Finally,the sample with x = 0.12 showed an ultrahigh W_(rec) value of 16.2 J/cm~3 and satisfactory of 82.3% at 97 kV/mm,outperforming most state-of-the-art counterparts.Furthermore,the ceramic also exhibited a large current density(CD) of 1268.4 A/cm~2 and power density(PD) of 177.6 MW/cm~3 at 28 kV/mm,offering prospective applications in high-power capacitors.This work not only achieved outstanding comprehensive energy storage performance in sodium niobate-based ceramics by modulating the antiferroelectric structure but also provided a feasible route to developing high-performance dielectric capacitors from the viewpoint of structure-property relationship.