Superior Capacitive Energy-Storage Performance in Pb-Free Relaxors with a Simple Chemical Composition
Zheng Sun, Ji Zhang, Huajie Luo, Yonghao Yao, Na Wang, Liang Chen, Tianyu Li, Changzheng Hu, He Qi, Shiqing Deng, Leighanne C. Gallington, Yuanpeng Zhang, Jöerg C. Neuefeind, Hui Liu, Jun Chen
Abstract
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/cm 3, 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 6 s 2 lone pair stereochemical active Bi into the classical BaTiO 3 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.