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 (eta) 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 AgNbO3 (AN) system simultaneously and obtain excellent U-rec and eta. The substitution of Sm3+ 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 Pr value. Due to the low P-r value and high BDS similar to 1300 kV.cm(-1), an excellent U-rec similar to 9.8 J.cm(-3) and P-D,P-max similar to 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.