Although K 0.5 Na 0.5 NbO 3 (KNN) possesses large maximum polarization and relatively high breakdown strength, the large remnant polarization constrains their practical applications as energy storage materials. In this work, through multi-element doping, (K 0.5−0.5 x Na 0.5−0.5 x Bi x )(Nb 1− x Sn 0.2 x Zn 0.6 x Ta 0.2 x )O 3 relaxor ferroelectrics were prepared. As the superparaelectric states (SPE) were adjusted to room temperature, orthorhombic, tetragonal, and cubic phases coexisted, accompanied by the highly dynamic polar nanoregions (PNRs). In particular, a high recoverable energy storage density of 4.5 J/cm 3 and an energy storage efficiency of 83% were achieved for the x = 0.125 ceramic, with the variations less than 11% and 4%, respectively, in the wide temperature range of 20–180 °C. These results demonstrate that the multiphase PNRs in the SPE state is an effective strategy for improving the energy storage performance of KNN-based ceramics.
Eco-friendly dielectric ceramics with excellent energy storage performance and dielectric temperature stability are the kernel parts of pulsed power devices in the next-generation. However, the contradiction between high breakdown electric field ( E b )and maximum polarization ( P max ) restricts the improvement of comprehensive performance. Herein, we report a novel strategy of entropy engineering in the superparaelectric state to address the above concerns. On the one hand, near-linear polarization response can be achieved in the superparaelectric state, which can be beneficial to obtain a large P max , low remnant polarization ( P r ) and slim P-E loops. On the other hand, the improvement of configuration entropy (Δ S config ) is conducive to refining grain size and domain size, enhancing bandgap width, and suppressing leakage current and interfacial polarization, thus the generation of large E b . Therefore, with the Δ S config increases from 0.98 R to 1.44 R, a giant energy storage density ( W rec ) of 8.11 J/cm 3 as well as a high efficiency ( η ) of 90.2 % are synchronously obtained. Significantly, the optimum sample shows outstanding dielectric temperature stability (Δ C / C 25°C ≤ ± 15 %, −55 ∼ 165 °C) in accordance with X8R. This work demonstrates that the medium entropy superparaelectrics are a shortcut to achieve next-generation ceramic capacitors with high comprehensive performance.
Lingling Wu,Bin He,Yonggang Shuai,Wuwei Feng,Weiping Gong,He Qi,Yuqin Liu
In response to the urgent need for efficient and reliable energy storage solutions, this study investigates the synergistic integration of high-entropy and superparaelectric engineering in Bi 0.5 Na 0.5 TiO 3 -K 0.5 Na 0.5 NbO 3 (BNT-KNN) ceramics, thereby achieving superior comprehensive energy storage performance in moderate electric fields. With the incorporation of Sr(Sc 0.5 Ta 0.5 )O 3 (SST), the BNT-0.2KNN-0.2SST demonstrates a high recoverable energy density ( W rec > 7 J/cm 3 ) and efficiency ( η > 95 %) at 420 kV/cm and the BNT-0.3KNN-0.15SST achieves W rec ~ 8 J/ cm 3 and η > 91 % at 500 kV/cm. The optimized ceramics achieve excellent comprehensive energy storage performance, exceptional high-temperature stability (20–240 °C) and fatigue resistance (≥10 6 cycles) under moderate electric fields (300–500 kV/cm) synchronously. The synergistic combination of high-entropy design and superparaelectric state regulation can effectively suppress the drastic fluctuations of the permittivity and the thermally induced phase transitions, thereby maintaining excellent performance across a broader temperature range and significantly enhancing the cyclic life of BNT-based ceramics through the reduction of defect generation and aggregation. The synergistic combination of these properties suggests promising applicability in next-generation capacitor devices, especially for energy storage applications requiring reliable performance in extreme operational environments.
危险品化学品经营许可证（带存储）