Achieving high discharge energy density and efficiency with NBT-based ceramics for application in capacitors

High-performance capacitors, which have high energy storage density as well as high discharge efficiency, are desired. In this study, we have designed and prepared novel and high quality (1 - x)(0.65Bi(0.5)Na(0.5)TiO(3)-0.35Bi(0.1)Sr(0.85)TiO(3))-x(K0.5Na0.5NbO3) [(1 - x)(BNT-BST)-xKNN, x = 0, 0.04, 0.06, 0.08, and 0.10] ceramics that demonstrated a remarkable energy storage capability, high efficiency, and ultrafast discharge speed. Particularly, the 0.94(BNT-BST)-0.06KNN ceramic possessed an excellent stored energy storage density (W-s = approximate to 3.13 J cm(-3)) and recoverable energy storage density (W-r = approximate to 2.65 J cm(-3)), and maintained a relatively high efficiency ( = approximate to 84.6%) at a relatively low electric field of 180 MV m(-1), which is superior to those of the lead-free BNT-based energy-storage materials. Moreover, excellent temperature (20-120 degrees C) and frequency (1-100 Hz) stabilities of the 0.94(BNT-BST)-0.06KNN ceramic were also achieved. More importantly, the 0.94(BNT-BST)-0.06KNN ceramic exhibited an ultrafast discharge rate ((0.9) = approximate to 1.01 s), a high level of discharge energy density (W-d -1.21 J cm(-3)), and excellent reliability in energy storage performance by consecutive cycling. Moreover, this study also provides an effective approach to attain large energy-storage capability along with high efficiency in BNT-based ceramics for application in pulsed power capacitors.