Superior Capacitive Energy-Storage Performance in Pb-Free Relaxors with a Simple Chemical Composition

• Published in: Journal of the American Chemical Society Vol. 145; no. 11; pp. 6194 - 6202
• Main Authors: Sun, Zheng, Zhang, Ji, Luo, Huajie, Yao, Yonghao, Wang, Na, Chen, Liang, Li, Tianyu, Hu, Changzheng, Qi, He, Deng, Shiqing, Gallington, Leighanne C., Zhang, Yuanpeng, Neuefeind, Joerg C., Liu, Hui, Chen, Jun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-03-2023; American Chemical Society (ACS)
• Subjects: INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.2c12200

Chemical design of lead-free relaxors with simultaneously high energy density (W rec) and high efficiency (η) for capacitive energy-storage has been a big challenge for advanced electronic systems. The current situation indicates that realizing such superior energy-storage properties requires highly complex chemical components. Herein, we demonstrate that, via local structure design, an ultrahigh W rec of 10.1 J/cm3, concurrent with a high η of 90%, as well as excellent thermal and frequency stabilities can be achieved in a relaxor with a very simple chemical composition. By introducing 6s 2 lone pair stereochemical active Bi into the classical BaTiO3 ferroelectric to generate a mismatch between A- and B-site polar displacements, a relaxor state with strong local polar fluctuations can be formed. Through advanced atomic-resolution displacement mapping and 3D reconstructing the nanoscale structure from neutron/X-ray total scattering, it is revealed that the localized Bi enhances the polar length largely at several perovskite unit cells and disrupts the long-range coherent Ti polar displacements, resulting in a slush-like structure with extremely small size polar clusters and strong local polar fluctuations. This favorable relaxor state exhibits substantially enhanced polarization, and minimized hysteresis at a high breakdown strength. This work offers a feasible avenue to chemically design new relaxors with a simple composition for high-performance capacitive energy-storage.