Gradient-Structured Ceramics with High Energy Storage Performance and Excellent Stability.

Owing to the high power density, eco-friendly, and outstanding stability, the lead-free ceramics have attracted great interest in the fields of pulsed power systems. Nevertheless, the low energy storage density of such ceramics is undoubtedly a severe problem in practical applications. To overcome this limitation, the lead-free ceramics with gradient structures are designed and fabricated using the tape-casting method herein. By optimizing the composition and distribution of the gradient-structured ceramics, the energy storage density, and efficiency can be improved simultaneously. Under a moderate electric field of 320 kV cm -1 , the value of recoverable energy storage density (W rec ) is higher than 4 J cm -3 , and the energy storage efficiency (η) is of ≥88% for 20-5-20 and 20-10-20. Furthermore, the gradient-structured ceramics of 20-10-0-10-20 and 20-15-0-15-20 possess high applied electric field, large maximum polarization, and small remnant polarization, which give rise to ultrahigh W rec and η on the order of ≈6.5 J cm -3 and 89-90%, respectively. In addition, the energy storage density and efficiency also exhibit excellent stability over a broad range of frequencies, temperatures, and cycling numbers. This work provides an effective strategy for improving the energy storage capability of eco-friendly ceramics.