Superior comprehensive energy storage properties in Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics

Seeking for high energy storage materials has become an urgent task in the circumstance of energy crisis. In this work, a series of relaxor ferroelectrics (1 − x)Bi0.5Na0.5TiO3-xSr0.7La0.2TiO3 ((1 − x)BNT-xSLT) with excellent energy storage performance were successfully fabricated. The SLT as a second component was doped into BNT and served three main functions: (1) efficiently decreased the grain size and increased the band gap and thus enhanced the breakdown electric field, (2) drove the ferroelectric phase gradually to a relaxor character, (3) reduced the tolerance factor (t) to defer the electric field of polarization saturation. Eventually, we achieved an impressive recoverable energy storage density (Wrec) of 4.14 J/cm3 and an ultrahigh energy storage efficiency (ƞ) of 92.2% simultaneously at 315 kV/cm in the ceramic of x = 0.45. Furthermore, the sample also exhibited an excellent stability against testing temperature, frequency and cycle, a high power density (182 MW/cm3) and a fast discharge speed (123 ns), all of which are ideal characteristics for high power energy storage devices.