Superior Energy Storage Properties and Optical Transparency in K0.5Na0.5NbO3‐Based Dielectric Ceramics via Multiple Synergistic Strategies

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-05, Vol.19 (19), p.n/a
• Main Authors: Chai, Qizhen, Zhang, Fudong, Zhou, Qiyuan, Peng, Zhanhui, Wu, Di, Liang, Pengfei, Wei, Lingling, Chao, Xiaolian, Yang, Zupei
• Format: Article
• Language: English
• Subjects: Ceramics; Discharge; Electronic devices; Energy storage; energy‐storage performance; Grain size; Microscopy; nanodomain; Nanotechnology; Optical properties; optical transparency; phase structure; Solid phases
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202207464

Eco‐friendly transparent dielectric ceramics with superior energy storage properties are highly desirable in various transparent energy‐storage electronic devices, ranging from advanced transparent pulse capacitors to electro‐optical multifunctional devices. However, the collaborative improvement of energy storage properties and optical transparency in KNN‐based ceramics still remains challenging. To address this issue, multiple synergistic strategies are proposed, such as refining the grain size, introducing polar nanoregions, and inducing a high‐symmetry phase structure. Accordingly, outstanding energy storage density (Wtotal ≈7.5 J cm−3, Wrec ≈5.3 J cm−3) and optical transmittance (≈76% at 1600 nm, ≈62% at 780 nm) are simultaneously realized in the 0.94(K0.5Na0.5)NbO3‐0.06Sr0.7La0.2ZrO3 ceramic, together with satisfactory charge‐discharge performances (discharge energy density: ≈2.7 J cm−3, power density: ≈243 MW cm−3, discharge rate: ≈76 ns), surpassing previously reported KNN‐based transparent ceramics. Piezoresponse force microscopy and transmission electron microscopy revealed that this excellent performance can be attributed to the nanoscale domain and submicron‐scale grain size. The significant improvement in the optical transparency and energy storage properties of the materials resulted in the widening of the application prospects of the materials. The optimized KNN‐based transparent ceramics with superior energy storage properties can be synthesized by refining the grain size, introducing polar nanoregions, and inducing a high‐symmetry phase structure. The nanoscale domains and submicron‐scale grains are confirmed by PFM and TEM. This lifts the dielectric breakdown strength and polarization difference. Highly symmetric crystal structure tailors remnant polarization and optical scattering.