Achieving excellent energy storage performances and eminent charging-discharging capability in donor (1-x)BT-x(BZN-Nb) relaxor ferroelectric ceramics

Prodigious efforts have been paid to explore excellent dielectric energy storage capacitors based on lead-free relaxor ferroelectric (RFE) ceramics in the last decades. However, there are rare candidates among them simultaneously possessing high energy storage density (W_rec), high efficiency (η), wide work temperature range and stable charge–discharge ability, etc. In this work, excellent energy storage performances are achieved in donor doped BaTiO₃ (BT)-based RFE ceramics by adopting two effective strategies of domain engineering and defect engineering. By introducing Bi(Zn_2/3-0.01xNb_1/3+0.01x)O_3+δ (BZN-Nb) into BT matrix, firstly, long-range ferroelectric polarization is broken to form polar nanoregions (PNRs) via domain engineering. Subsequently, Nb donor substitution results in a dramatic increase in bulk resistivity (ρ_b) accompanied by a significant increase in dielectric breakdown electric strength (E_DBS) via defect engineering. Finally, a combination of relative high P_max, much low P_r and giant E_DBS ensures that the optimum composition x = 0.3 in (1-x)BT-x(BZN-Nb) system exhibits high W_rec of 5.96 J/cm³ and high η of 89.5 %. Such properties together with good thermal stability (up to 220 °C), good fatigue endurance (for 10⁶ cycles) and eminent charging-discharging capability (e.g., discharge time t_0.9 ∼ 50 ns, current density C_D ∼ 1.17 kA/cm² and power density P_D ∼ 175.38 MW/cm³ at 300 kV/cm) suggest that the 0.7BT-0.3(BZN-Nb) ceramic is a very promising candidate among lead-free dielectric capacitors for energy storage applications.