Enhanced recoverable energy storage density and efficiency in (1 − x)Ba0.85Ca0.15Zr0.1Ti0.9O3-xSrTiO3-MnO2 lead-free ceramics

Abstract

Lead-free dielectric capacitors have attracted much attention in pulsed power systems due to their rapid charge/discharge rate. However, their recoverable energy storage density (W_rec) and efficiency (η) still need further improvement to meet the requirements for their application in energy storage devices. In this article, SrTiO₃ (ST) and MnO₂ were introduced to Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) to obtain a (1 − x)BCZT-xST solid solution, where morphotropic phase boundary ferroelectric BCZT possesses high polarization, paraelectric ST has a high dielectric breakdown strength (E_b), and the 0.3 mol% MnO₂ contributes to the dense and fine-grained microstructure as a sintering aid. A high E_b of 436 kV cm⁻¹, large ferroelectric polarization of 33.0 μC cm⁻², and small remnant polarization of 2.1 μC cm⁻² were obtained in the 0.3BCZT-0.7ST ceramic. As a result, a large W_rec of 5.36 J cm⁻³ and a high η of 82.2% were simultaneously achieved. Moreover, the 0.3BCZT-0.7ST ceramic exhibits a large DC discharge energy density of 5.63 J cm⁻³ and an ultrafast discharge time (t_0.9) of 46 ns, and therefore an extremely high power density (P_D) of 367.8 MW cm⁻³ and a large current density (C_D) of 1337.6 A cm⁻², two essential parameters for practical application in high-power devices. These results highlight the potential applications of the 0.3BCZT-0.7ST ceramic in pulsed power capacitors with high energy storage density and provide a comprehensive guideline for the control of BaTiO₃-based dielectric capacitors.