Ultrahigh energy storage capacity with superfast discharge rate achieved in Mg-modified Ca0.5Sr0.5TiO3-based lead-free linear ceramics for dielectric capacitor applications

Abstract

For the urgent demand of environmental protection and energy conservation, it is of great significance to develop environmentally-friendly dielectric ceramics with outstanding characteristic of energy storage and quick charge discharge capacity. For this study, we applied a strategy to achieve the enhancement of energy storage performance in (Ca0.5Sr0.5)1-xMgxTiO3 (abbreviate as CSMTx, x = 0.005, 0.010, 0.020, 0.040) linear ceramics based on the introduction of Mg2+ ion. Scanning electron microscopy and complex impedance measurement reveal that Mg2+ ion doping can refine grain size and increase grain boundary density, which results in grain boundary barrier strengthening owing to high-resistance grain boundaries. As a result, the marvellous energy storage properties, including an ultrahigh recoverable energy density of 2.88 J/cm3 combined with a giant energy efficiency of 90% are concurrently obtained in (Ca0.5Sr0.5)0.99Mg0.01TiO3 ceramic at an enhanced breakdown field (460 kV/cm). Meanwhile, this composition ceramic also exhibits the superior stability of frequency (1–1000 Hz) and temperature (20–100 °C) with minimal variation. In addition, the actual performance of ceramic capacitors in operation can be evaluated via the pulsed charge-discharge process. Delightedly, the superfast discharge speed (t0.9 = 20.4 ns), large current density (CD) of 421.23 A/cm2 and ultrahigh power density (PD) of 25.27 MW/cm3, as well as prominent thermal stability (20–100 °C) are synchronously produced in the CSMT2 ceramic. These merits qualify the unleaded linear ceramic as a competitive candidate for high-power capacitor applications, which offers a practicable approach for exploration on high-performance dielectric materials.