Authors: Shiyu Zhou, Yucheng Zhou, Linhai Li, A. Pelaiz-Barranco, Xuefeng Chen, Genshui Wang, Yiwei Chen, Rongjiang Wang, Konstantin Nefedev, Tengfei Hu, Dawei Wang, Tongqing Yang

Dielectric energy storage capacitors play a pivotal role in pulsed power systems. Herein, we demonstrate a breakthrough in dielectric energy storage by engineering ​local polarization units in high-entropy multilayer ceramic capacitors (MLCCs). By incorporating equimolar Ba2+/Sr2+ dual cations, we precisely smoothen the phase transition and stabilize a nanoscale phase-coexistence state in an NBT-based matrix, which simultaneously retain robust local polar units while disrupting long-range domain order. This unique configuration, validated by atomic-resolution HAADF-STEM and phase-field simulations, enables a high reversible polarization and breakdown strength. The optimized MLCCs achieve an ultrahigh recoverable energy density of 18.2 J cm−3 with 91% efficiency, coupled with exceptional thermal stability and fatigue resistance. This work establishes a general design paradigm for high-entropy dielectrics for energy storage by controlling local polarization configurations.