Achieving enhanced comprehensive energy storage performances under moderate electric field in NaNbO3-Bi(Mg3/4W1/4)O3 relaxor ferroelectric ceramics via the cold sintering process

NaNbO 3 ceramics, recognized as lead-free dielectric energy storage material, suffer from limited energy storage efficiency due to their substantial remnant polarization, which hinders their practical application. The design and engineering of relaxor ferroelectrics represent a promising strategy for substantially improving their comprehensive energy storage performance. In this study, (1- x )NaNbO 3 - x Bi(Mg 3/4 W 1/4 )O 3 (NN-BMW) relaxor ferroelectric ceramics were fabricated through a conventional solid-state sintering process. A systematic investigation was carried out to evaluate the microstructural characteristics, dielectric behavior, and energy storage performance of the NN-BMW ceramics. Among the ceramic samples, the 0.9NaNbO 3 -0.1Bi(Mg 3/4 W 1/4 )O 3 (0.9NN-0.1BMW) ceramic demonstrated the highest recoverable energy density of 2.03 J/cm 3 and the lower energy storage efficiency under an electric field of 290 kV/cm. To further enhance the energy storage performance of the 0.9NN-0.1BMW ceramic, a cold sintering technique combined with post-annealing was employed. By optimizing the post-annealing temperature, the 0.9NN-0.1BMW ceramic treated at 1000 °C exhibited significantly enhanced recoverable energy density of 2.59 J/cm 3 and energy storage efficiency of 76.5 %, surpassing the sample prepared by conventional sintering at 1150 °C. This work illustrates a low-energy, eco-friendly method of synthesizing NN-based relaxor ferroelectric ceramics with superior comprehensive energy storage performances.