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Abstract Excellent electric energy discharging efficiency and fatigue resistance are two critical factors in high energy storage capacitor for electronic device and high-power system with fast charging-discharging speed. Here, we report on designing and preparing the thick films of BaZr 0.2 Ti 0.8 O 3 (BZT20) bilayer ceramics (BLCs) (∼40 μm in thickness) using a tape casting method. In this ABO 3 -structured perovskite ceramics, the B position of Ti was occupied by 20 mol% Zr atoms, which leads to order-disordering and random fields in the single phase with both the tetragonal (space group P 4 mm) and rhombohedral (space group m-3m). And therefore, the relaxors possess a heterogeneous polar state at the nanoscale and their long-range domains are disrupted. Consequently, a non-hysteretic arc-shaped unipolar polarization-electric frield loop (P-E loop) in which the curve obtained under a considerable high electric field of 80 MV m−1 and the curve under depolarization are overlaped. As such, a large energy storage density (U e) of ∼6.2 J cm−3 with the discharging efficiency of ∼98% and a considerable fatigue resistance over 22 k cycles at a wide temperature range from 253 to 393 K (−20 °C–120 °C) are obtained. The attractive electric performance of this BLCs films demonstrates that this sort of relaxor ceramics is one of promising materials for capacitors with little calorigenic electronic power areas. Highlights • Relaxor BaZr 0.2 Ti 0.8 O 3 bilayer ceramics are prepared using a tape casting method. • Non-hysteretic P-E loop curve under polarization overlaps the depolarization part. • A large energy density of ∼6.2 J cm−3 with the efficiency of ∼98% is obtained. • A considerable fatigue resistance of 22 k cycles at −20 °C to 120 °C is obtained. [ABSTRACT FROM AUTHOR]

The lead lanthanum zirconate titanate (PLZT) nanoscale particles with a cubic crystal cell and the favorable surface activity obtaining from sol-gel method are adopted as the filter. And a ferroelectric poly (vinylidene fluoride- co - trifluoroethylene) (P(VDF- co -TrFE)) copolymer synthesizing by an atom transfer radical polymerization (ATRP) process from commercial poly (vinylidene fluoride- co - chlorotrifluorethylene) (P(VDF- co -CTFE)) is selected as the polymer matrix to form the PLZT/P(VDF- co -TrFE) 0–3 nanocomposites. By expressing the influence of conductivity of polymer on the distribution of polarizing electric field on the ceramic particles and polymer matrix, we find that the relative high conductivity of the P(VDF- co -TrFE) may result in a high electrical field applying on the PLZT particles, which will further enhance the dielectric and ferroelectric properties of the composites. Consequently, for the combining contributions of ionic and dipole polarizations, the PLZT/P(VDF- co -TrFE) nanocomposite film with 20wt% PLZT possesses a very large dielectric constant of 85 at 100 Hz, a high ferroelectric property (D m ∼7.5 μC/cm 2 and D r ∼5 μC/cm 2 ) at a small polarizing electrical field of 37.5 MV/m, and an excellent piezoelectric constant of −31 pC/N after thermal polarizing under 5 MV/m at 100 °C, respectively. Considering their good mouldability, favorable ferroelectric and piezoelectric properties, the flexible PLZT/P(VDF- co -TrFE) film provides a reliable reference of the potential using of the ceramic/polymer nanocomposites in sensor, actuator, and other mechanical-electrical energy transforming devices. [ABSTRACT FROM AUTHOR]

Transitional metal selenides are regarded as promising electrode materials for battery-type electrodes on account of their superior electrical conductivity and high redox activity. It is expected to further improve their electrochemical performance by reasonable designing of the metal selenides' components and construction of novel nanostructures. Thus, in this article, self-supported sugar gourd-like (Ni,Co)Se 2 /(Ni,Co)Se 2 composites on carbon cloth are prepared by a facile approach. The theoretical calculations indicate that the (Ni,Co)Se 2 has higher conductivity and larger adsorption energy of OH- than that of NiSe 2 and CoSe 2 , thus effectively improving the kinetics of their electrochemical reactions. Thanks to synergetic effects from the active materials and their hierarchical nanostructures, the prepared sugar gourd-like (Ni,Co)Se 2 /(Ni,Co)Se 2 /CC nanoarrays achieve a high areal specific capacity of 1.278 mAh/cm2 (220.34 mAh/g) at 2 mA/cm2 and 88.9 % capacity retention after 5000 cycles. Furthermore, the flexible hybrid supercapacitor based on the designed nanocomposite demonstrates a high energy density of 0.7051 mWh cm−2 at the power density of 1.6303 mW cm−2 with extraordinary cycling stability. Such eminent energy storage performances strongly certificate that the obtained (Ni,Co)Se 2 /(Ni,Co)Se 2 /CC electrode is a potential battery-type electrode material for supercapacitor application. [Display omitted] • The sugar gourd-like (Ni,Co)Se 2 /(Ni,Co)Se 2 /CC nanoarrays were successfully designed. • Due to core-shell structure, nanoarrays reflect abundant active sites. • DFT provide theoretical support for the ameliorated electrochemical performance. • (Ni,Co)Se 2 /(Ni,Co)Se 2 /CC//AC HSC device achieves outstanding energy density. [ABSTRACT FROM AUTHOR]

The rational design of hierarchical nanostructure consisting of multiple components with remarkable electrochemical performance is regarded as a significant technique for fabricating high-performance energy storage devices. Herein, self-supported tree-like (Ni,Co)Se 2 /Ni(OH) 2 heterogeneous nanoarrays on carbon cloth (CC) used as electrode materials of supercapacitors (SCs) are designed and synthesized by a multi-step approach. The (Ni,Co)Se 2 core can boost electron transport due to excellent conductivity, and the shell layer of Ni(OH) 2 nanoflakes improves the surface area. Profiting from the cooperative effects of two active materials and core-shell architecture, the tree-like (Ni,Co)Se 2 /Ni(OH) 2 composite delivers a superior capacity, outstanding rate capability and still retain 151.3 mAh g−1 after 3000 charge/discharge cycles. Meanwhile, the flexible hybrid supercapacitor (HSC) fabricated by the (Ni,Co)Se 2 /Ni(OH) 2 and activated carbon (AC) also manifests a satisfied energy density of 0.79 mWh cm−2 under 1.35 mW cm−2. Therefore, it can be considered that the as-prepared hierarchical (Ni,Co)Se 2 /Ni(OH) 2 nanoarrays are promising candidate for HSC devices in energy storage and conversion. • The tree-like (Ni,Co)Se 2 /Ni(OH) 2 core-shell nanoarrays were successfully designed. • The (Ni,Co)Se 2 /Ni(OH) 2 electrode exhibits superior electrochemical performance. • Due to construct heterogeneous core-shell structure, the hierarchical nanoarrays possess rich active sites. • The assembled HSC device achieves outstanding energy density. [ABSTRACT FROM AUTHOR]

In this paper, a unique UV assisted low temperature sol-gel method was developed to prepare ZrO 2 pore-sealing film on the micro-arc oxidation (MAO) layer coated magnesium alloy. It was found that 100 °C UV irradiated ZrO 2 film (UV-ZrO 2) showed a denser surface, as compared with those prepared by traditional sol-gel route and heat treated at 100–425 °C. Correspondingly, the magnesium alloys with UV-ZrO 2 sealed MAO layer showed an enhanced anti-corrosion property. The photochemistry analysis indicated that UV light can break the organic species at low temperature, resulting in the amorphous ZrO 2 film with more flat surface. Therefore, this kind of ZrO 2 films irradiated by UV light at low temperature can play a good sealing role in protecting the MAO layer coated magnesium alloys from corrosion. • ZrO 2 films are obtained on MAO magnesium alloys through a unique UV assisted sol-gel method. • ZrO 2 film irradiated by UV light at low temperature shows a dense and smooth surface. • UV irradiated ZrO 2 film enhances the anticorrosion properties of the MAO magnesium alloys. [ABSTRACT FROM AUTHOR]

• N-rGO/CS microflowers with high mass loading were prepared. • The introduction of N-rGO could increase the specific surface area and enhance conductivity. • N-rGO/CS//AC quasi-solid-state HSCs were fabricated. • A high energy density of 4.65 mWh cm−3 were achieved for the assembled HSCs. [Display omitted] In this work, we prepared N-doped reduced graphene oxide/Co 0.85 Se (N-rGO/CS) microflowers through a two-step method. Since introducing N-doped rGO, the fabricated N-rGO/CS electrode with a high mass loading (~8.83 mg/cm2) exhibits high areal specific capacity of 0.522 mAh/cm2 (4.24 F/cm2) at 1 mA/cm2, and a long-term cycling stability (85.8% of capacity retention after 6000 charge-discharge cycles). This is mainly because N-doped rGO can increase specific area and electrical conductivity, enhance the electrochemical activity and effectively facilitate the electron/ion transport between the electrode and electrolyte. Besides, the quasi-solid-state hybrid supercapacitors (HSCs) assembled by the N-rGO/CS delivers a high volumetric specific capacity of 5.82 mAh/cm3 at 1 mA/cm2, excellent energy density of 4.65 mWh/cm3 under 10.5 mW/cm3 and eminement cycle stability (87.6% retention over 6000 cycles at 10 mA/cm2). [ABSTRACT FROM AUTHOR]