Enhanced energy storage in tungsten bronze-based ferroelectrics and MLCCs via a multi-coating engineering

High-power pulsed systems demand dielectric capacitors with high energy density and efficiency. Although perovskite ceramics dominate this field, simultaneously achieving high performance and fatigue endurance remains a significant challenge. Our study addresses this aim by incorporating a Ba1-xSrxTiO3 second phase into tungsten bronze-type Ba1-xSrxNb2-yTayO6 matrix, followed by chemical coating with a SiO₂ layer. The prepared ceramics achieve an energy density of 21.1 J/cm³ with an efficiency of 84.5%. Furthermore, by combining a rational multilayer ceramic capacitor design with the thickness effect, an energy density of 23.2 ± 1.2 J/cm³ and an improved efficiency of 92.8 ± 0.4% are attained, representing a record energy density for tungsten bronze-based ceramics and capacitors. The dual-core-shell structure and compositional gradients induce lattice mismatch, boosting polarization and breakdown strength. The fabricated devices also demonstrate remarkable stability under varying frequency, temperature, and fatigue cycling conditions. The authors construct tungsten bronze–perovskite composites with a SiO₂ coating, forming a dual-core-shell architecture. This design yields a high energy density of 23.2 J/cm³ and 92.8% efficiency in multilayer ceramic capacitors, due to enhanced polarization and breakdown strength, alongside excellent thermal and fatigue stability.