Inverse High‐Entropy Design Enables Superior Energy Storage in Moderate and High Electric Fields

Dielectric capacitors are critical for pulsed power systems, yet their energy storage performance (ESP) requires further enhancement. While high-entropy design improves breakdown strength (E_b), it often stabilizes a non-polar phase, limiting polarization (P_m) and restricting high ESP to impractically high electric fields. Here, we propose an inverse high-entropy design strategy to overcome this limitation. Using the quasi-linear high-entropy ceramic Bi_1/6Na_1/6Sr_1/6Ca_1/6Li_1/6La_1/6TiO₃ (BNSCLLT) as a matrix, we incorporated the classical ferroelectric BaTiO₃ (BT) to precisely regulate the polar structure. Introducing BT successfully induced a weakly polar tetragonal phase within the primarily cubic matrix, promoting polar nanoregions and optimizing the polarization response. This strategy effectively balances a significant increase in P_m with a controlled reduction in E_b. Consequently, the 0.7BNSCLLT-0.3BT and 0.6BNSCLLT-0.4BT compositions achieved superior performance with W_rec ∼ 10.9 J/cm³, η ∼ 88% at 600 kV/cm and W_rec ∼ 11.6 J/cm³, η ∼ 86% at 580 kV/cm, respectively. Notably, the 0.5BNSCLLT-0.5BT composition also attained excellent ESP (W_rec ∼ 9.8 J/cm³, η ∼ 80%) at a moderate field of 475 kV/cm. This work demonstrates the efficacy of the inverse high-entropy design in achieving high-performance energy storage across both high and moderate electric fields, offering a new paradigm for developing advanced dielectric materials.