Next-generation advanced high/pulsed power capacitors rely heavily on dielectric ceramics with high energy storage performance. However, thus far, the huge challenge of realizing ultrahigh recoverable energy storage density (Wrec) accompanied by ultrahigh efficiency (η) still existed and has become a key bottleneck restricting the development of dielectric materials in cutting-edge energy storage applications. Here, we propose a high-entropy strategy to design “local polymorphic distortion” including rhombohedral-orthorhombic-tetragonal-cubic multiphase nanoclusters and random oxygen octahedral tilt, resulting in ultrasmall polar nanoregions, an enhanced breakdown electric field, and delayed polarization saturation. A giant Wrec ~10.06 J cm−3 is realized in lead-free relaxor ferroelectrics, especially with an ultrahigh η ~90.8%, showing breakthrough progress in the comprehensive energy storage performance for lead-free bulk ceramics. This work opens up an effective avenue to design dielectric materials with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.

Strain engineering has emerged as a powerful tool to create new states of known materials with excellent performance. Here, we show a general and practically realizable method via interphase strain to obtain a new super tetragonality providing giant polarization. This method is illustrated for the case of PbTiO3, where we report a c/a ratio of up to 1.238 in epitaxial composite thin films, compared to that of 1.065 in bulk PbTiO3. These thin films of super-tetragonal structure possess an unprecedented giant remanent polarization, 236.3 μC/cm 2 , which is almost twice the value of all known ferroelectrics. The tetragonal phase is stable up to 725 °C as compared to the bulk's transition temperature of 490 °C. The present interphase strain approach could provide a new avenue to enhance the physical properties of materials with respect to their multiferroic, photonic, superconductor, and energy-harvesting behavior.

Understanding the roles of metals and atomic structures in activating various elementary steps of electrocatalytic reactions can help rational design of binary or ternary catalysts for promoting activity toward desirable products via favorable pathways. Here we report on a newly developed ternary Au@PtIr core−shell catalyst for ethanol oxidation reaction (EOR) in alkaline solutions, which exhibits an activity enhancement of 6 orders of magnitude compared to AuPtIr alloy catalysts. Analysis of in situ infrared reflection absorption spectra for Au@PtIr and its bimetallic subsets, Au@Pt and PtIr alloy, found that monatomic steps and Au-induced tensile strain on PtIr facilitate C−C bond splitting via ethanol dissociative adsorption and Ir promotes dehydrogenation at low potentials. As evidenced by the CO band being observed only for the PtIr alloy that is rather inactive for ethanol dissociative adsorption, we propose that splitting the C−C bond at the earliest stage of EOR activates a direct 12-electron full oxidation pathway because hydrogen-rich fragments can be fully oxidized without CO as a poisoning intermediate. The resulting synergy of complementary effects of Au core and surface Ir leads to an outstanding performance of Au@PtIr for EOR as characterized by a low onset potential of 0.3 V and 8.3 A mg −1 all-metals peak current with 57% currents generated via full ethanol oxidation.

Lead‐free dielectric ceramics with ultrahigh energy storage performance are the best potential stocks used in next‐generation advanced pulse power capacitors. Here, an ultrahigh recoverable energy storage density Wrec of ≈7.57 J cm−3 and a large efficiency η of ≈81.4% are first realized in (Bi0.5K0.5)TiO3 (BKT)‐based relaxor ferroelectric ceramics with an ultrahigh Vickers hardness Hv ≈ 8.63 Gpa by adding BaTiO3 and NaNbO3 in order to synergistically design the domain and microstructure in multiscale, leading to the existence of ultrasmall polar nanoregions, ultrafine grain size, compact grain boundaries, dense microstructure, and large band gap Eg simultaneously. Encouragingly, an excellent energy storage temperature stability (Wrec ≈ 4.31 ± 0.25 J cm−3, η ≈ 86 ± 5%, 20–200 °C), frequency stability (Wrec ≈ 5.14 ± 0.12 J cm−3, η ≈ 81.3 ± 1.2%, 5–100 Hz), and excellent charge/discharge performance (power density PD ≈ 103.2 MW cm−3, discharge energy density WD ≈ 2.4 J cm−3, discharge rate t0.9 ≈ 130 ns) are also achieved in BKT‐based ceramics. The results demonstrate that BKT‐based ceramics can be very competitive lead‐free relaxors for energy storage capacitors in pulsed power devices.

To realize the ultrahigh W rec , it is essential to improve the above factors simultaneously.Recently, numerous studies have shown that linear dielectrics, ferroelectrics, and antiferroelectrics are difficult to achieve breakthroughs in energy-storage performance owing to the lack of high-polarization genes, poor efficiency caused by high P r , unstable antiferroelectric phase and antiferroelectric-ferroelectric phase transition, respectively. [2] To further enhance the W rec , transforming ferroelectrics and antiferroelectrics into relaxors is a simple but effective method, leading to the decreased domain size and P r . Interestingly, the strategies for the formation of relaxors are diverse. For relaxor antiferroelectrics, ultrahigh W rec of 12.2 and 18.5 J cm −3 can be achieved in NaNbO 3 (NN)-based ceramics using nanodomain engineering, causing a diffuse antiferroelectric to ferroelectric phase transition behavior to reduce the possibility of breakdown by reducing large transient currents and volume changes. [3] However, relatively low efficiency (η < 80%) limits their actual applications. The strategy of constructing phase boundary was designed to obtain excellent comprehensive energy-storage properties in AgNbO 3 (AN)-based ceramics. [4] For relaxor ferroelectrics, many strategies, such as composition adjustment, [5] domain/nanodomain engineering, [6] high-entropy design [7] were proposed to improve the energy-storage performance. Unfortunately, in addition to high-entropy strategy, there is no effective design to realize ultrahigh energy storage density (W rec ≥ 10 J cm −3 ) in relaxor ferroelectrics, making them comparable to relaxor antiferroelectric energy storage ceramics in competitiveness and development potential. [3,8] The control of polarization, domain or polar nanoregions (PNRs) configuration is an amusing approach to design new dielectric materials with enhanced energy-storage performance. Unmatched temperature range, [9] nanoscale polarization mismatch and reconstruction, [10] and crossover region [11] were adopted to form different domain configurations such as coexisting Ti-rich and Bi-rich PNRs, and coexisting nanodomain and PNRs. However, low W rec (<4 J cm −3 ) and medium η (≈80%) were obtained in relaxors due to the insufficient E b , fast polarization saturation and the existence of large size nanodomains. It is common that enhanced relaxation can result in a decreased polarization, and some methods should be used Lead-free dielectric ceramics with ultrahigh energy-storage performance are the core components used in next-generation advanced pulse power capacitors. However, the low energy storage density largely hinders their development towards miniaturization, lightweight, and integration. Here, an effective strategy of constructing local diverse polarization is designed in superparaelectrics to realize an ultrahigh energy storage density of ≈10.59 J cm −3 as well as a large efficiency of ≈87.6%. The excellent comprehensive energy-storage performance is mainly attributed to the desi...