Synergistic enhanced energy storage performance of NBT-KBT ceramics by K0.5Na0.5NbO3 composition design

(1-x)(0.8Na0.5Bi0.5TiO3-0.2K0.5Bi0.5TiO3)-xK0.5Na0.5NbO3 (x = 0, 0.1, 0.2, 0.3, 0.4) (NBT-KBT-KNN) ceramic solid solution was synthesized by solid phase method through designing KNN composition. XRD, Raman and SEM results show that NBT-KBT-KNN ceramics form solid solutions with a stable perovskite structure. The dielectric temperature spectrum and impedance spectrum analysis confirmed that the relaxor ferro-electrics (RFE) properties enhanced with increasing KNN content. The piezoresponse force microscopy (PFM) results reveal that the introduced KNN disrupts the microdomains of NBT-KBT ceramics and pro-motes the formation of nanodomains, leading to enhanced energy storage properties. The breakdown electric field strength (BDS) was also increased with increasing KNN content, and maximum value was obtained at x = 0.2. The addition of KNN can obviously improve energy storage performance (ESP). At 255 kV cm-1, x = 0.2 produced excellent ESP with recoverable energy storage density (Wrec), amazingly normalized response (xi), efficiency (eta) and maximum polarization (Pmax) are 3.38 J cm-3, 132.55 J kV-1 m-2, 85.4 %, and 45.76 mu C cm-2, respectively. ESP is also stable in terms of frequency and temperature at (1-100 Hz) and (20-140 degrees C). At 120 kV cm-1, the discharge energy density (Wdis), power density (PD), Current density (CD) and time for releasing 90 % of total energy density (t0.9), are 0.202 J cm-3, 23.43 MW cm-3, 390.42 A cm-2, and 56.6 ns. These findings demonstrate that NBT-KBT-KNN ceramics have the ability to be reliable energy storage and pulse power capacitors.(c) 2023 Elsevier B.V. All rights reserved.