Ultrahigh Energy Storage Density and Efficiency in Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub>-Based Ceramics via the Domain and Bandgap Engineering
Meng Wang, Qin Feng, Chaoying Luo, Yuchen Lan, Changlai Yuan, Nengneng Luo, Changrong Zhou, Toyohisa Fujita, Jiwen Xu, Guohua Chen, Yuezhou Wei
Abstract
Environmentally friendly lead-free dielectric ceramics have attracted wide attention because of their outstanding power density, rapid charge/dischargerate, and superior stability. Nevertheless, as a hot material in dielectric ceramic capacitors, the energy storage performance of Na0.5Bi0.5TiO3-based ceramics has been not satisfactory because of their higher remnant polarization value and low dielectric breakdown strength, which is a problem that must be urgently overcome. In this work, the (1 – x) (0.6Na0.5Bi0.5TiO3 – 0.4Sr0.7Bi0.2TiO3) – xBa(Mg1/3Ta2/3)O3 (BNST-xBMT) systems were designed based on a dual optimization strategy of domain and bandgap to solve the above problems. As a result, a record-breaking ultrahigh energy density and excellent efficiency (Wrec = 8.58 J/cm3, η = 93.5%) were obtained simultaneously under 565 kV/cm for the BNST-0.08BMT ceramic. The introduction of Sr0.7Bi0.2TiO3 induces the formation of nanodomains in BNT-based ceramics, leading to slim P-E curves, and the further modification of Mg/Ta reduces the grain sizes and increases the bandgap width, resulting in significant enhancement of the dielectric breakdown strength. Moreover, excellent stability and superior discharge performance (Wd = 4.7 J/cm3, E = 320 kV/cm) in the BNST-0.08BMT ceramic were also achieved. The results suggest that the BNST-0.08BMT ceramic shows potential applicability for dielectric energy storage ceramics. Simultaneously, the composition-design concept in the system provides a good reference for the further development of ceramic dielectric capacitors.