Significant improvement of comprehensive energy storage performance and transparency in Sr0.7La0.2TiO3-doped (K,Na)NbO3 lead-free ceramics

Although transparent ceramics are highly desirable for practical applications, it is challenging to achieve outstanding energy storage properties and high transparency simultaneously in (K, Na)NbO3 ceramics. Herein, through a combination of modifying crystal symmetry and refining domain size and grain size, a high recoverable energy storage density Wrec ≈ 4.04 J cm−3, a high efficiency η ≈ 73 %, and good optical transmittance (≈ 77 % at 2000 nm, ≈ 60 % at 780 nm) are realized. Of particular significance is that an excellent discharge energy density of ≈ 2.43 J cm−3, a superior discharge current density of ≈ 1551 A cm−2, and a high discharge power density of ≈ 233 MW cm−3 are simultaneously achieved in 0.93(K0.5Na0.5)NbO3-0.07 Sr0.7La0.2TiO3 ceramics, outperforming all reported KNN-based transparent ceramics. This work exhibits a paradigm for achieving high performance KNN-based ceramics, and the transparent dielectric ceramics reported here are expect to expand hybrid electronic device applications.