Grain size engineered lead-free ceramics with both large energy storage density and ultrahigh mechanical properties

Zetian Yang, Feng Gao, Hongliang Du, Li Jin, Leilei Yan, Qingyuan Hu, Ying Yu, Shaobo Qu, Xiaoyong Wei, Zhuo Xu, Yan Jie Wang

Research output: Contribution to journalArticlepeer-review

553 Scopus citations

Abstract

Lead-free dielectric ceramics with both a high recoverable energy storage density (W rec ) and excellent mechanical performance are highly desirable for practical applications in next-generation advanced pulsed power capacitors (APPCs). However, lead-free dielectric ceramics exhibit low W rec owing to small breakdown strength (E b ) and poor mechanical properties because of their large pore size and low relative density, which restrict devices miniaturization and operation in severe environments. Here, we propose a new strategy, namely, grain size engineering, to develop K 0.5 Na 0.5 NbO 3 (KNN)-based ceramics with both an extremely high W rec and large mechanical properties. Interestingly, a large W rec of 2 J cm −3 was achieved in 0.9K 0.5 Na 0.5 NbO 3 -0.1BiFeO 3 (0.9KNN-0.1BF) ceramics at 206 kV cm −1 , which is superior to other lead-free dielectric ceramics under moderate electric fields (<220 kV cm −1 ). Encouragingly, the hardness (H) of 0.9KNN-0.1BF ceramics reached 2.45 GPa, which is approximately 5 times higher than that of pure KNN ceramics (0.45 GPa). Moreover, the bending strength (σ f ), elastic modulus (E) and compression strength (σ c ) of 0.9KNN-0.1BF ceramics are also enhanced by ~200% over those of pure KNN ceramics. Compared with other lead-free dielectric ceramics, grain size engineered 0.9KNN-0.1BF is the first high-performance ceramic material with both an exceptionally large W rec and ultrahigh mechanical properties, which can accelerate the practical use of APPCs. Most importantly, the findings in this work will not only provide a guideline for developing other lead-free dielectric ceramics with both extremely high energy storage properties and superior mechanical performance but also open a window to the mechanical properties of dielectric ceramics for APPCs.

Original languageEnglish
Pages (from-to)768-777
Number of pages10
JournalNano Energy
Volume58
DOIs
StatePublished - Apr 2019

Keywords

  • Energy storage density
  • Grain size engineering
  • Mechanical properties
  • Potassium-sodium niobate

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