Ultrahigh energy storage density in lead-free NaNbO3-based ceramics through multilayer structure design

Dielectric capacitors have been widely employed in advanced pulse power technology and electronic devices. Nevertheless, the insufficient recoverable energy storage density and efficiency pose a major obstacle for realizing further miniaturization and integration. Herein, multilayer structured NaNbO 3 -based ceramics, composed of random and textured layers with identical chemical compositions, were prepared via the tape casting technique. As a result, in the sample with two random layers outside and one textured layer in middle, a remarkable recoverable energy storage density of 11.9 J/cm 3 with an efficiency of 76.8 % is achieved concurrently at an electric field of 728 kV/cm. The finite element simulation implicates that this approach effectively tunes local electric potential, electric field and polarization distributions. More importantly, the investigated ceramics exhibited benign stability over a wide temperature range (20–100 °C), frequency range (1–500 Hz) and cycling up to 10 5  cycles. This work not only provides a multilayer structured ceramic applicable to novel high-performance dielectric capacitors, but also proposes a feasible strategy for regulating the local electric field and polarization distributions and finally boosting the energy storage performance.