Synergistic Enhanced Energy Storage Performance of Nbt-Kbt Ceramics by K0.5na0.5nbo3 Composition Design

Abstract

(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 ferroelectrics (RFE) properties enhanced with increasing KNN content. 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 (ξ), efficiency (η) and maximum polarization (Pmax) are 3.38 J·cm–3, 132.55 J·kV–1·m–2, 85.4%, and 45.76 μC·cm–2, respectively. ESP is also stable in terms of frequency and temperature at (1–100 Hz) and (20–140 °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.

Keywords: (Na0.5Bi0.5)TiO3, K0.5Na0.5NbO3 composition design, Relaxor ferroelectric, Energy storage