Grain size modulated (Na0.5Bi0.5)0.65Sr0.35TiO3-based ceramics with enhanced energy storage properties

Ferroelectric ceramics, as a potential candidate for high-power energy storage capacitors, lies in their excellent recoverable energy storage density (W-rec) and outstanding efficiency (eta) in practical applications. Herein, a new type of lead-free ceramics (1-x)(Na0.5Bi0.5)(0.65)Sr0.35TiO3-xBiMg(0.5)Sn(0.5)O(3) or (1-x)NBST-xBMS was prepared with the aim of enhancing the breakdown strength (Eb) and reducing the energy storage loss through grain refinement. It was found that E-b of 0.9NBST-0.1BMS reaches 405 kV/cm due to the reduction in the grain size of ceramic and thus the extremely high ratio of grain boundary resistance to grain resistance. Besides, a remarkable energy storage performance was obtained, that is, W-rec and eta are ~ 6.68 J/cm(3) and 89.1% at 405 kV/cm, respectively, along with excellent stability in terms of frequency, temperature, and fatigue endurance. The outstanding energy-storage performance is resulted from modulating the grain size via doping the moderate content of Bi3+ and Mg2+/Sn4+, which is beneficial to increase the breakdown field by increasing resistivity under high electric field while increasing the grain boundary activation energy and promote the formation of a relaxor state at the same time. More importantly, energy storage potential (defined as W-rec/E-b) is up to 0.01649 mu C/cm(2), being the highest value reported so far for BNT-based ceramics in energy-storage application. Our results pave the way for practical applications of NBST-based ferroelectric capacitors with excellent energy storage performance.

Automated summary

A new type of lead-free ceramics with excellent energy storage performance was successfully prepared by controlling the grain size and doping of impurities, providing new possibilities for practical applications of ferroelectric ceramics in energy storage.