Novel lead-free NaNbO₃-based relaxor antiferroelectric ceramics with ultrahigh energy storage density and high efficiency

The development of environmentally friendly ceramics for electrostatic energy storage has drawn growing interest due to the wide application in high power and/or pulsed power electronic systems. However, it is difficult to simultaneously achieve ultrahigh recoverable energy storage density (W_rec > 8 J/cm³) and high efficiency (η > 80 %), which restricts their application in the miniaturized, light weight and easy integrated electronic devices. Herein, the novel NaNbO₃-(Bi_0.8Sr_0.2)(Fe_0.9Nb_0.1)O₃ relaxor antiferroelectric ceramics, which integrates the merits of antiferroelectrics and relaxors, are demonstrated to exhibit stabilized antiferroelectric phase and enhanced dielectric relaxor behavior. Of particular importance is that the 0.88NN-0.12BSFN ceramic achieves giant electric breakdown strength E_b = 98.3 kV/mm, ultrahigh W_rec = 16.5 J/cm³ and high η = 83.3 %, as well as excellent frequency, cycling and thermal reliability simultaneously. The comprehensive energy storage performance of NN-BSFN not only outperforms state-of-the-art dielectric ceramics by comparison, but also displays outstanding potential for next-generation energy storage capacitors.