High‐Entropy Superparaelectrics With both Ultrahigh Energy Storage Performance and Broad‐High Temperature Stability

ABSTRACT Achieving high recoverable energy density ( W rec ) and energy storage efficiency ( η ) concurrently with robust temperature stability remains a significant challenge for dielectric energy storage ceramics. Here, a high‐entropy‐superparaelectric (HE‐SPE) synergistic strategy is proposed based on La(Mg 0.5 Zr 0.5 )O 3 (LMZ) modified (Bi 0.2 Na 0.2 Ba 0.2 Sr 0.2 Ca 0.2 )TiO 3 (BNBSCT) system. By promoting cationic disorder, the high‐entropy (HE) effect induces lattice strain and random octahedral tilting that synergistically enhance resistivity and potential uniformity for a high breakdown field ( E b ). Owing to broadening the superparaelectric (SPE) region to room temperature, the system enables quick switching of polar nanoclusters through lowered energy barriers, thus achieving a high dynamic polarization response and near‐zero remnant polarization ( P r ). Consequently, the (1 – x )BNBSCT‐ x LMZ ceramics with x = 0.15 acquire an outstanding W rec of 13.51 J cm −3 and a high η of 94.6% under a high E b of 750 kV cm −1 . Furthermore, the wide temperature window of polar nanocluster coexistence enables the ceramic to achieve excellent comprehensive energy storage performance across a wide temperature range (25–200°C). This work provides new route to develop dielectric materials with high energy storage performance and excellent temperature stability.