Sandwich structured lead-free ceramics based on Bi0.5Na0.5TiO3 for high energy storage

With the rapid development of electronic information technology and the rising environmental concerns as well as the tendency of electronic devices towards miniaturization and integration, enhancing the energy storage properties of lead-free ceramic capacitors is one of the imperative issues. Although a large number of efforts have been contributed to optimize the energy storage properties of lead-free ceramics, the conflict between the polarization and electric breakdown strength seriously impedes the improvement of energy storage density significantly. Herein, inspired by the layered composites of sandwich, the sandwich structured lead-free ceramics based on Bi0.5Na0.5TiO3 were designed and fabricated to overcome the above challenge effectively. The theoretical simulations and experiment results demonstrate that the polarization and electric breakdown strength can be optimized synchronously via the sandwich structured design. An ultrahigh recoverable energy storage density of ~ 6 J cm−3 and a nearly ideal energy conversion efficiency of ~ 95% can be obtained for the prepared sandwich structured lead-free ceramics. Meanwhile, the maximum applied electric field can be enhanced to more than 500 kV cm−1. The energy storage capabilities also exhibit outstanding stability over a broad temperature range, frequency range and cycle numbers. These results reveal that the Bi0.5Na0.5TiO3-based lead-free ceramics of this study have a great potential for high energy storage capacitors applications.