Tao Deng, Jiyang Xie, Zhen Liu, Liqiang He, Zhichao Hong, Haonan Peng, Dong Wang, Cosme Milesi-Brault, Teng Lu, Yonghong Chen, Zhisheng Lin, Wanbiao Hu, Brahim Dkhil, Yun Liu, Genshui Wang, Junhao Chu
As promising candidates for next-generation energy storage devices in electrical and electronic systems, lead-free multilayer ceramic capacitors face increasingly high performance requirements. To counteract the usual trade-off between energy storage density and efficiency, we here propose a high-entropy design that directly harnesses diverse oxide symmetries to targetedly engineer competing orders and tune the composition into the crossover region between relaxor ferroelectric and superparaelectric states. Atomic-scale structural analysis reveals high-entropy ceramic develops pronounced local polarization fluctuation and dispersed oxygen octahedral rotations, which enhance relaxor behavior and reduce switching barrier. Consequently, superior recoverable energy density of 20.64 J cm-3 and high efficiency of 94.2% are obtained in our designed high-entropy Bi0.5Na0.5TiO3-based multilayer ceramic capacitors, along with excellent thermal/anti-fatigue stability and charge-discharge capabilities. This work provides a transferable strategy to engineer competing orders in lead-free dielectric materials and successfully achieves high-entropy multilayer ceramic capacitors with superior energy storage performance. Authors design lead-free high-entropy multilayer ceramic capacitors where entropy tunes competing polar orders, enabling high energy density and efficiency with fast discharge and robust thermal and cycling stability.