Li Yang,Tang Ming-Yang,Zhang Zhong-Gang,Li Qi,Li Jing-Lei,Xu Zhuo,Liu Gang,Li Fei
BaTiO 3 ceramics are difficult to withstand high electric fields, so the energy storage density is relatively low, inhabiting their applications for miniaturized and lightweight power electronic devices. To address this issue, we added Sr 0.7 Bi 0.2 TiO 3 (SBT) into BaTiO 3 (BT) to destroy the long-range ferroelectric domains. Ca 2+ was introduced into BT-SBT in the form of CaTiO 3 (CT), which has the effect of inhibiting the movement of A-site defects to reduce dielectric loss and refining the grains to increase the breakdown field strength. In addition, we have increased the density and grain uniformity of ceramics by repeated rolling of the green samples through the viscous polymer processing (VPP), to further increase the breakdown electric field. The BT-SBT-CT ceramics exhibit the high recoverable energy storage density of 4.0 J·cm −3 under electric field of 480 kV·cm −1 . Its recoverable energy storage density varies by less than 8% in the temperature range of 30–150 °C, indicating good temperature stability of the energy storage performance. In this work, the energy storage performance of barium titanate-based ceramics was greatly improved by transforming ferroelectrics into relaxor ferroelectrics and VPP method, which can bring new inspiration for the research of energy storage ceramics. Graphical abstract
Yan Yan,Xinyu Zeng,Tao Deng,Fukang Chen,Lishun Yang,Zhanbing He,Li Jin,Gang Liu
Porous BaTiO 3 -based relaxor ferroelectric ceramics with lamellar structure were achieved by ice templating method, and the rheological properties of ceramic slurry for freeze casting were deeply studied. Epoxy resin was then backfilled to generate ceramic–epoxy resin composites. Ceramic–epoxy composites with a lamellar structure were obtained when using a slurry with a ceramic content of 45 wt.%. The nanoindentation results showed that the introduction of ceramic materials into the epoxy resin can significantly improve the penetration resistance and hardness of the material. The dielectric and ferroelectric properties of the composites were also characterized. The interaction between the highly coupled dipoles in the polymers results in a decrease in the breakdown field strength of the composite. The dielectric constant reached up to ∼800. At 220 kV/cm, W rec = 0.62 J/cm 3 , and η was ∼80%. At low frequencies, W rec was ∼0.16 J/cm 3 , which indicated good stability.
A serials of relaxor ferroelectrics of Sr 0.7 Bi 0.2 TiO 3 ceramics with different grain sizes were prepared by a conventional sintering (CS) and a two-step cold sintering aided process (CSP) method. The microstructure, dielectric and energy storage performance of the synthesized ceramics were systematically studied. Owing to the involvement of CSP, grain size is reduced to submicrometer scale, and uniform and dense morphology are achieved at a lower sintering temperature compared with the CS method. As a consequence, high critical electric field (420 kV/cm), a good recoverable energy storage density (3.32 J/cm 3 ), and a superior energy efficiency (92.84 %) can be realized for the ceramic via CSP sintered at 1170 °C. Meanwhile, it also exhibits good stability over wide ranges of measuring frequencies and temperatures, and increasing cycles to 10 7 . A high power density (85.46 MW/cm 3 ) is achieved due to a very fast discharge rate (∼61.7 ns). Moreover, the synthesized ceramic demonstrates an ultrahigh hardness of ∼ 8.73 GPa. These results indicate that CSP is a feasible solution to achieve outstanding comprehensive dielectric energy storage performance by utilizing the synergistic effects of grain refinement and densification.
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