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capacitors), dielectric capacitors are promising candidates for advanced pulsed power applications owing to their high power density and fast charge/discharge speed. [6][7][8] Ceramic dielectrics show excellent temperature stability and mechanical robustness, are promising materials for use in extreme conditions. [9] Anti-ferroelectric ceramics (such as PbTiO 3 -and Pb(Zr,Ti)O 3 -based dielectrics) display double polarization-electric field (P-E) loops, which have tremendous potential for realizing high energy density. [10][11][12] However, most of these materials are Pbbased, whose toxic nature causes a series of environmental problems. Thus, leadfree ceramics have attracted considerable attention as a replacement to Pb-based materials. [7,[13][14][15][16][17][18] Until now, the low energy storage performance (low energy storage density of <4 J cm −3 and/or inferior efficiency of <80%) of lead-free ceramic capacitors hardly meet the increasing integration and miniaturization requirements. [19][20][21][22] Thus, it is imperative to improve the energy storage performance of lead-free ceramic capacitors.As shown in the schematic of Figure 1a, the energy storage density and efficiency of the dielectric capacitors are governed by the maximum polarization (P max ), remanent polarization (P r ), and dielectric breakdown strength (E BDS ). The combination of a large P max , small P r , and high E BDS is essential for realizing ultrahigh energy storage density and efficiency. Considering that the energy loss density (W loss ) is an inevitable part of ferroelectric ceramics, the recoverable energy storage density (W rec ) and energy efficiency (η) are key parameters for evaluating the energy storage performance of nonlinear dielectric ceramic capacitors. [9,17,23] It has been reported that BiFeO 3 (BF) possesses very high spontaneous polarization (≈100 µC cm −2 ), which is superior to most perovskite ferroelectrics, including BaTiO 3 , Bi 0.

materials (FE), relaxor ferroelectric materials, and antiferroelectric materials (AFEs). [2][3][4][5][6][7] Among them, antiferroelectric materials are preferred candidates for obtaining an exceptional energy storage density due to the high saturation polarization (P s ) and zero remnant polarization (P r ). [7] A schematic illustration of the energy storage mechanism of antiferroelectric materials is shown in Figure S1 in the Supporting Information. The W tot and W rec of antiferroelectrics are calculated by the area between the phase switching loop and the polarization axis and can be described by the following equations [7,8] where P max , P r , and E represent the maximum polarization, the remnant polarization, and applied electric field, respectively. The difference between W rec and W tot represents the energy dissipation (W loss ) and the ratio of W rec to W tot is defined as the energy efficiency, which can be described by the following equation [7,8] 100% 100% rec tot rec rec l ossIn comparison with lead-free antiferroelectric ceramics, PbZrO 3 -based antiferroelectric ceramics have always been a more popular topic because of their superior energy storage performance. It is particularly interesting that a minor variation of doping ions at the A or B site of the perovskite (ABO 3 ) structure may display huge differences in materials properties. Hence, scholars have continuously focused on investigating the structure-property relationships of PbZrO 3 -based AFE ceramics, such as tailoring the phase transition characteristics of AFE ceramics via ions doping, or utilizing unique fabrication methods to increase the energy storage density, and so forth. [8][9][10][11][12] Recently, a record-high recoverable energy storage density of 11.18 J cm −3 was obtained in Sr-doped (Pb 0.94 La 0.02 Sr 0.04 )(Zr 0.9 Sn 0.1 ) 0.995 O 3 AFE ceramics that prepared by tape-casting method. [9] However, the large electrical hysteresis resulted from the first-order antiferroelectric-ferroelectric (AFE-FE) phase transition has always been an apparent drawback of AFE ceramics, [13] leading to the high energy dissipation, Antiferroelectric ceramics with extraordinary energy-storage density have gained exponentially soaring attention for their applications in pulsed power capacitors. Nevertheless, high energy dissipation is a deficiency of antiferroelectric materials. The modulation of Ba/La-doped (Pb 0.91 Ba x La 0.06−2x/3 ) (Zr 0.6 Sn 0.4 )O 3 (x = 0.015, 0.03, 0.045, 0.06) antiferroelectric ceramics is aimed at increasing the energy efficiency and obtaining an ideal energy storage density. The traditional solid-state reaction is exploited for ceramics fabrication and all prepared samples exhibit an ultralow electrical hysteresis due to the local structural heterogeneity, as verified by Raman spectroscopy. Of particular importance is the fact that the (Pb 0.91 Ba 0.045 La 0.03 )(Zr 0.6 Sn 0.4 ) O 3 ceramic possesses an excellent recoverable energy storage density (W rec = 8.16 J cm −3 ) and a remarkable energy efficiency (η = 92.1...

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An incommensurate modulated antiferroelectric phase is a key part of ideal candidate materials for the next generation of dielectric ceramics with excellent energy storage properties. However, there is less research carried out when considering its relatively low polarization response. Here, the incommensurate phase is modulated by stabilizing the antiferroelectric phase and the energy storage performance of the incommensurate phase under ultrahigh electric field is studied. The tape‐casting method is applied to construct dense and thin ceramics. La3+ doping induces a room‐temperature incommensurate antiferroelectric orthorhombic matrix. With little Cd2+, the extremely superior energy storage performances arose as follows: when 0.03, the recoverable energy storage density reaches ≈19.3 J cm‐3, accompanying an ultrahigh energy storage efficiency of ≈91% (870 kV cm‐1); also, a giant discharge energy density of ≈15.4 J cm‐3 emerges during actual operation. In situ observations demonstrate that these superior energy storage properties originate from the phase transition from the incommensurate antiferroelectric orthorhombic phase to the induced rhombohedral relaxor ferroelectric one. The adjustable incommensurate period affects the depolarization response. The revealed phase‐transition mechanism enriches the existing antiferroelectric–ferroelectric transition. Attention to the incommensurate phase can provide a reference for the selection of the next generation of high‐performance antiferroelectric materials.