Enhanced energy storage performance in SrTiO3-modified NBT-based lead-free ceramics via a stepwise strategy

Abstract

Lead-free dielectric ceramics are gaining prominence in energy storage due to their superior power density and rapid charge/discharge capabilities. However, Na_0.5Bi_0.5TiO₃ (NBT)-based ceramics stand out as particularly promising dielectric materials, but face two critical challenges: excessive remnant polarization and inadequate dielectric strength, which substantially limit their energy storage performance. To enhance energy storage performance in lead-free ferroelectric ceramics, a stepwise optimization method was adopted in this study. The strategy combines compositional engineering through precise elemental ratio adjustment to tailor microstructural characteristics, and processing optimization to significantly enhance breakdown strength (E_b). This dual-approach methodology has been experimentally demonstrated to effectively boost the energy storage capabilities of the ceramic system. The incorporation of SrTiO₃ as a modifier successfully induced nanoscale domain structures in the 0.91Na_0.5Bi_0.5TiO₃-0.09K_0.7La_0.1NbO₃ (NBT-KLN-based) system, yielding desirable slim P-E loops. Subsequently, the viscous polymer processing (VPP) technique was utilized to minimize defects and boost density, thereby significantly enhancing the E_b. The optimized NBT-KLN-0.20ST-vpp composite ceramics demonstrated remarkable energy storage properties, achieving a high W_rec of 5.34 J/cm³ and efficiency of 82% under 460 kV/cm. This study not only offers a viable strategy for improving NBT-based ceramics but also lays the groundwork for designing advanced energy storage materials, demonstrating promising applications in compact power electronics.