Significantly Enhanced Energy Storage Performance of Lead-Free BiFeO 3 -Based Ceramics via Synergic Optimization Strategy.

Owing to the merits of giant power density and ultrafast charge-discharge time, dielectric capacitors including ceramics and films have inspired increasing interest lately. Nevertheless, the energy storage density of dielectric ceramics should be further optimized to cater to the boosting demand for the compact and portable electronic devices. Herein, an ultrahigh recoverable energy storage density W rec of 13.44 J/cm 3 and a high efficiency η of 90.14% are simultaneously realized in BiFeO 3 -BaTiO 3 -NaTaO 3 relaxor ferroelectric ceramics with high polarization P max , reduced remanent polarization P r , and optimized electric breakdown strength E b . High P max originates from the genes of BiFeO 3 -based ceramics, and reduced P r is induced by enhanced relaxor behavior. Particularly, a large E b is achieved by the synergic contributions from complicated internal and external factors, such as decreased grain size and improved resistivity and electrical homogeneity. Furthermore, the ceramics also exhibit satisfactory frequency, cycling and thermal reliability, and decent charge-discharge property. This work not only indicates that the BiFeO 3 -based relaxor ferroelectric materials are promising choices for the next-generation electrostatic capacitors but also paves a potential approach to exploit novel high-performance dielectric ceramics.