A combinatorial improvement strategy to enhance the energy storage performances of the KNN based ferroelectric ceramic capacitors

With the increasing demand for miniaturization and integration in electronic equipment, environmental-friendly K0.5Na0.5NbO3 (KNN) based lead-free energy storage ceramic capacitors have caused extensive concern not only for their ultrahigh power density but also for ultrafast charging/discharging rates. However, their recoverable energy storage density (W-rec) and efficiency (eta) are loss, poor due to the large energy loss (W-loss) and low breakdown electric field (E-b). In this work, a combinatorial improvement strategy is proposed to enhance the energy storage performance of KNN-based ceramics. First, the introduction of 0.05Bi(Zn-0.5(Ti1-xZrx)(0.)(5))O-3 (BZTZ) solid solution in pure KNN ceramics extremely destroys the long-range polar ordering and forms the PNRs, which effectively decreases the remnant polarization (P-r) and enhances eta. Second, the substitution of Zr to Ti ions reduces the migration of grain boundary and thereby inhibits grain growth. Third, the BZTZ solid solution as a high-K insulator improves the band-gap energy (E-g) of the KNN-based ceramics. Both of them could boost Eb. Finally, the x = 0.75 ceramic with an excellent W-rec (3.70 J cm(-3)) and eta (75.3%) at a particularly large E-b (340 kV cm(-1)) was successfully obtained. The combinatorial improvement strategy in this work provides a novel way to enhance the energy storage performance of the lead-free dielectric capacitors. [GRAPHICS] .