Harnessing Multisite High-Entropy Architecture for Ultrahigh Energy Storage Multilayer Capacitors

High energy density lead-free dielectric capacitors play a pivotal role in state-of-the-art electrical and electronic systems. Nevertheless, the low energy storage capacities have persistently posed a significant impediment to the ongoing trend toward the miniaturization and integration of electronic devices. Here, we report an equimolar high-entropy relaxor ferroelectric multilayer capacitor that demonstrates exceptional energy storage performance by harnessing flexible multisite tetragonal tungsten bronze (TTB) high-entropy architecture. Our findings reveal that the equimolar high-entropy design results in NbO₆octahedra distortion, disrupting long-range ferroelectric order while preserving strong off-center displacements along the polar axis at a local scale. This unique structure characteristic of high-entropy TTB not only enhances its relaxor feature, reducing hysteresis, but also maintains high polarizability under applied electric fields. Consequently, our high-entropy TTB multilayer ceramic capacitors achieved an unprecedented recoverable energy density of 20.2 J·cm^–3, accompanied by a notably enhanced efficiency of 93.8%. This approach opens the door for the development of innovative functional ceramics and devices with prominent energy storage capability by designing flexible multisite high-entropy architecture.