Energy-storage properties of low-temperature Co-fired BNT-ST/AgPd multilayer lead-free ceramic capacitors

Abstract

A lead-free 0.6Bi0.5Na0.5TiO3-0.4SrTiO3 ceramic doped with Nb2O5, CuO and MnO2 additives (BNSr0.4TNbxCu0.8Mn0.15) was synthesized at a relatively low firing temperature of 1050 °C. Using this composition, multilayer ceramic capacitors with AgPd inner electrodes were successfully prepared by a tape-casting method for energy storage applications. Due to the high polarization Pmax and low hysteresis, the largest recoverable energy storage density Wrec value of 1.9 J/cc and high efficiency η of 89% were obtained in the BNSr0.4TNb2.5Cu0.8Mn0.15 composition under a low electric field of 170 kV/cm. The multilayer BNSr0.4TNb2.5Cu0.8Mn0.15/Ag75Pd25 capacitors contain 30 active layers, in which the thickness of a single ceramic layer was approximately 27 μm. Under a low electric field of 270 kV/cm, excellent energy storage performance was observed in multilayer capacitors, with a Wrec of 2.83 J/cc and η of 85%. The capacitors demonstrate the temperature insensitive properties that the variation in Wrec was less than 5% between 25 °C and 100 °C. These results indicate that this ceramic capacitor is a promising candidate for lead-free energy storage applications.