AgNbO₃-Based Multilayer Capacitors: Heterovalent-Ion-Substitution Engineering Achieves High Energy Storage Performances

The demand for miniaturization and integration in next-generation advanced high-/pulsed-power devices has resulted in a strong desire for dielectric capacitors with high energy storage capabilities. However, practical applications of dielectric capacitors have been hindered by the challenge of poor energy-storage density ( U rec ) and efficiency (η) caused by large remanent polarization ( P r ) and low breakdown strength (BDS). Herein, we take a method of heterovalent ion substitution engineering in combination with the multilayer capacitor (MLCC) technology and thus achieve a large maximum polarization ( P max ), zero P r, and high BDS in the AgNbO 3 (AN) system simultaneously and obtain excellent U rec and η. The substitution of Sm 3+ for Ag + in Sm x AN+Mn MLCCs at x ≥ 0.01 decreases the M 1 –M 2 phase transition temperature, and the antiferroelectric (AFE) M 2 phase appears at room temperature, which is beneficial to achieving a low P r value. Due to the low P r value and high BDS ∼ 1300 kV·cm –1, an excellent U rec ∼9.8 J·cm –3 and P D,max ∼ 34.8 MW·cm –3 were achieved in Sm x AN+Mn MLCCs at x = 0.03. The work suggests a paradigm that can enhance the energy storage capabilities of AFE MLCCs to meet the demanding requirements of advanced energy storage applications.