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

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_0.5Zr_0.5)O₃ (LMZ) modified (Bi_0.2Na_0.2Ba_0.2Sr_0.2Ca_0.2)TiO₃ (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-xLMZ 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.