Novel lead-free ceramic capacitors with high energy density and fast discharge performance

Abstract

Dielectric capacitors with high energy storage density, good frequency/temperature stability, and fast charge-discharge capability are highly demanded in pulsed power systems. In this work, we design and prepare a novel lead-free 0.88BaTiO3-0.12Bi(Li1/3Zr2/3)O3 (0.12BLZ) relaxor ferroelectric ceramic for dielectric capacitor application. The microstructure, conduction mechanism, dielectric properties, and energy storage behavior of the 0.12BLZ ceramic were systematically studied. The impedance analysis demonstrates that the introduction of BLZ enhances the insulation ability and breakdown strength of the 0.12BLZ ceramic. Meanwhile, the introduction of BLZ can also reduce the polarization nonlinearity of the BaTiO3 matrix due to the weakly coupled relaxor behavior. As a result, ultrahigh energy storage density (Urec) of 3 J/cm3 and efficiency (η) of 93.8% were simultaneously achieved in 0.12BLZ ceramic. The significantly improved Urec was far superior to most of the recently reported lead-free bulk ceramics. Additionally, excellent frequency and temperature stability (variations of Urec less than 15% in different frequencies (1–100 Hz) and temperatures (25–140 °C)) can be also observed. In addition, the 0.12BLZ ceramic presents an ultrahigh current density (Ddis) of 759 A/cm2, a giant power density (Pm) of 37.9 MW/cm3, and a fast discharge time of 80 ns. The pulsed charge-discharge performances of the 0.12BLZ ceramic are obviously better than those of other lead-free ceramics. These results indicate that the 0.12BLZ relaxor ferroelectric may be an excellent candidate material applied for pulsed power systems.