Enhancing energy storage density of BNT-ST-based ceramics by a stepwise optimization strategy on the breakdown strength

Abstract

High discharge-energy-storage-density (Wdis) ceramics with high breakdown strength (BDS) are in high demand nowadays. However, enhancing BDS always comes at the cost of significantly reduction on polarization. In this work, a stepwise-optimization strategy combining two-step sintering and chemical-coating is proposed to enhance BDS of 0.6Bi0.5Na0.5TiO3-0.4SrTiO3 (BNT-ST) ceramics. Finally, significant enhancement on BDS, delayed saturation polarization and considerable polarization are successfully achieved simultaneously. The BNT-ST ceramic prepared via chemical-coating and two-step sintering (BNT-ST@Si-TSS) maintains a high polarization (44.36μC/cm2 at 270 kV/cm) and achieves a high Wdis of 3.14 J/cm3. BDS and Wdis of BNT-ST@Si-TSS ceramics are enhanced by nearly 70 % and 60 % than that of BNT-ST ceramics prepared by traditional sintering, respectively. Besides, BNT-ST@Si-TSS ceramics exhibit excellent thermal stability (∆Wdis≤4.6 % among 30–140 ℃) and outstanding fatigue stability (∆Wdis≤2.7 % after 106 cycles). This work offers a feasible avenue to optimize ceramic characteristics step-by-step, showing great potential in high-energy-storage fields.