Ultrafast charge-discharge and enhanced energy storage properties of lead-free K_0.5Na_0.5NbO₃-based ceramics

For dielectric capacitors in pulsed power systems, ultrafast charge-discharge rates and good energy storage performances are essential. The relatively low efficiency eta and the low energy density of potassium sodium niobate ceramics will restrict their applications. In this work, a local distortion of the crystal structure of ceramics is made by introducing the Bi and Ce ions, promoting the growth of polar nano-regions, resulting in more obvious relaxation behavior and lower remnant polarization P-r. The average grain size is reduced, further increasing of breakdown strength. Eventually, fine comprehensive energy storage performances and good mechanical properties are simultaneously obtained. Enhanced recoverable energy storage density W-rec (similar to 5.30 J/cm(3)) and a high energy storage efficiency eta (similar to 76.81%) are achieved in 0.970(K0.5Na0.5)NbO3-0.030CeBiO(3) (KNN-0.030CB) ceramics with an ultrafast discharge rate t(0.9) (31 ns) and a high current density (1008.5 A/cm(2)). All of these results indicate that this work provides a resultful way to design excellent comprehensive properties for advanced energy storage materials.