Weakly coupled relaxor construction in lead-free ferroelectrics with simple composition for superior energy-storage performance

Abstract

The development of advanced environmentally friendly energy storage capacitors is critical to meet escalating demands of pulsed power systems. However, challenges persist in enhancing both the recoverable energy density (W_rec) and efficiency (η) simultaneously. In the present study, a strategy involving domain configuration modulation, achieved by simple single rare earth ion doping, was proposed to enhance the energy-storage performance of BaTiO₃. The designed Ba_1−1.5xLa_xTiO₃ (BLT-x) ceramics exhibited an ultrahigh W_rec of 9.2 J cm⁻³ and η of 85.0% when x = 0.10. Furthermore, the origin of the superior performance was revealed through first-principles calculations and atomic-scale displacement analysis. The introduction of La generated intense structural fluctuations in the ordered ferroelectric domains, leading to relaxors with weakly coupled polar nanoregions and delayed saturation polarization. Such factors, combined with enhanced E_b, contributed to elongated P–E loops and ultimately ultrahigh W_rec and η. Meanwhile, the BLT-0.10 ceramic demonstrated exceptional temperature stability (−40–120 °C), frequency stability (10–250 Hz) and fatigue stability (10⁶ cycles), along with notable charging–discharging capabilities. The present research not only provides a potential candidate for advanced pulsed power systems, but also offers a novel strategy for achieving superior energy-storage performance in perovskite ferroelectrics through single rare earth ion-doping.