Nano‐Micro Engineering Modulating High‐Entropy Multilayer Ceramic Capacitor for High‐Performance Energy Storage

Abstract High‐performance dielectric capacitors for energy storage play a pivotal role in advancing pulsed power technology across multidisciplinary applications. Nevertheless, the concurrent optimization of reversible polarization and breakdown strength to achieve high energy storage performance remains a significant challenge. Here, a nano‐micro engineering strategy is proposed, implemented through a high‐entropy approach, to simultaneously improve polarization and breakdown strength in (Na _1/4 Bi _1/4 Sr _1/2 )TiO ₃ ‐based matrix, which enables the realization of excellent energy storage density and efficiency in multilayer ceramic capacitors. The engineering achieves the inhomogeneous structure in the nanoscale and the homogeneous structure in micrometer‐scale based on discrete nanoscale polar phases, contributing to high polarization with low hysteresis and enhanced resistivity, respectively. Benefitting from the nano‐micro structure, the multilayer ceramic capacitor demonstrates a large energy density of 15.6 J cm ⁻³ along with a high efficiency of 90.2%. This work pioneers a novel approach to developing high‐performance energy storage multilayer ceramic capacitors.