Improving Energy Storage Properties of KNN Ceramic through Composition Modification

In this study, (1-x)K0.5Na0.5NbO3-xBa0.5Sr0.5(Zn1/3Nb2/3)O3, [(1-x)KNN-xBSZN] lead-free relaxor ceramics were fabricated by a conventional solid-state reaction method. XRD and Raman spectra confirm the R-C phase transition of the ceramics. The incorporation of BSZN effectively suppresses grain growth, enhanced the electrical resistivity, and improved the relaxation behavior. By analyzing the ferroelectric property of the sample under breakdown field, it is found that when x = 0.08, the ceramic demonstrates the smallest variation in polarization ( increment P = 12.43 mu C cm-2), the highest recoverable energy storage density (W rec = 0.8 J cm-3) and energy storage efficiency (eta = 58.8%). The enhancement of energy storage is attributed to the introduction of BSZN, which effectively suppresses grain growth and improves the relaxation behavior of the ceramics. The results show that the ceramic enables be used in pulsed-power systems at low electrical field.