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In this study, dopamine@BaTiO3 whiskers/P(VDF-HFP) nanocomposite films with high charge energy density were successfully prepared by a simple solution casting method. The BaTiO3 whiskers has been obtained under an optimized two-step hydrothermal condition. To alleviate the interfacial incompatibility, the BaTiO3 whiskers are modified by dopamine coating. The structure and morphology of dopamine@BaTiO3 whiskers have been well confirmed through XRD, SEM, and TEM. Further performance characterization of the nanocomposite films indicates that higher addition of BaTiO3 whiskers gives better dielectric properties and energy density. However, enhanced energy storage and high breakdown strength of nanocomposite can be obtained simultaneoulsy under suitable content.The maximal discharged energy density of the nanocomposite films with 5 vol% dopamine@BaTiO3 whiskers can reach 9.02 J/cm3, and the discharged efficiency remain 46.29% at 300 MV/m. These findings reveal a straightforward approach to improve the performance of the nanocomposite films. [ABSTRACT FROM AUTHOR]

With revolutionary electric vehicles and the smart grid fast developing, more advanced energy storage technologies become quite crucial issues. Li-ion batteries (LIBs) and Na-ion batteries (NIBs) are considered as the most promising electrochemical energy storage technologies. Low-dimensional nano-structural electrode materials can greatly increase the specific capacity, but they still suffer from poor cycling and rate performances due to their serious self-aggregations. Constructing 3D structures, such as micro/nano-structures and free-standing electrodes, is a quite promising method to address the above issues. Such 3D structures can simultaneously avoid the disadvantages of low-dimensional nanomaterials, and preserve their advantages. As one group of promising high-capacity and low-cost electrode materials, vanadium-based oxides have exhibited an quite attractive electrochemical performance for energy storage applications in many novel works. However, their systematic reviews are quite limited, which is disadvantageous to their further development. Herein, this article provides an overview of vanadium-based oxides in the applications of LIBs and NIBs by focusing mainly on the aspect from low-dimensional nanomaterials synthesis to 3D micro/nano-structures and free-standing electrodes fabrication. Moreover, a feasible strategy to controllably fabricate the 3D micro/nano-structure for the whole vanadium-based oxides family is presented. Furthermore, and importantly, a quite promising solution method for the practical commercialized applications of vanadium oxides cathode materials in the future is proposed, i.e., fabricating the 'vanadium oxides-based cathode/solid electrolyte/Li metal anode-type' all solid-state secondary-ion batteries. [ABSTRACT FROM AUTHOR]

Dielectric capacitors with high power density are essential components in advanced electronic and micro-electronic products. Nevertheless, the limited energy storage density and efficiency, coupled with poor performance at elevated temperatures, severely restrict their usefulness. In this work, Ta was introduced to the (Ag 0.80 Bi 0.04 Sr 0.04)NbO 3 ceramic prepared via the hydrothermal-synthesized powders to improve the room- and high-temperature energy storage performance. A large breakdown strength of 729 kV/cm, a high recoverable energy storage density of 8.5 J/cm3 and a benign energy efficiency of 75.6% were simultaneously achieved in (Ag 0.80 Bi 0.04 Sr 0.04)(Nb 0.85 Ta 0.15)O 3 ceramics. Moreover, the larger energy storage efficiency (83.5%) at elevated temperatures than room temperature, the benign frequency and cycle stability foreshow great potential in realizing the application of capacitors at high-temperatures. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are considered promising energy storage devices owing to the abundant reserve and low-cost accessibility of Na resources. However, such batteries suffer from poor electrochemical performance due to the larger diameter of Na ions (0.106 nm). In this study, nitrogen-doped carbon-coating interlayer-expanded MoS 2 porous nanosheets (MoS 2 @N–C) were synthesized, and their structural, morphological, and electrochemical properties were characterized. The XPS and EDS indicated the successful introduction of carbon into the MoS 2 nanosheets. The interlayer spacing for (002) plane was increased from 0.62 nm to 0.78 nm corresponding to the shift toward lower angles shown in XRD. The MoS 2 @N–C exhibited an impressively high reversible capacity of 352 mAh/g at a current density of 100 mA/g after 200 cycles; this capacity is five times higher than that of bare MoS 2. Moreover, MoS 2 @N–C showed excellent rate performance due to the boosted diffusion of Na ions. The observed improvement in the electrochemical performance of MoS 2 @N–C demonstrates that the combination of suitable composite materials and interlayer expansion are effective strategies for battery technologies based on the storage of large ions. Image 1 • A high-temperature mixing method under hydrothermal conditions was utilized. • CTAB acts as intercalating reagent to perform interlayer engineering for MoS 2 @N–C. • The porous, flower-like few-layered MoS 2 @N–C nanosheets were obtained. • The interlayer spacing of (002) planes of MoS 2 @N–C increased from 0.62 nm to 0.78 nm. • The physical mechanisms for the enhanced electrochemical properties were addressed. [ABSTRACT FROM AUTHOR]

The unique antiferroelectric behavior of AgNbO 3 ceramics has great potential for energy storage applications, which have attracted increasing attention. However, the relatively low recoverable energy storage density, energy efficiency and breakdown strength of AgNbO 3 ceramics severely limit their application in practice. In the present work, (Bi 0.2 Sr 0.7)TiO 3 was introduced to improve the relaxation behavior in AgNbO 3 ceramics via two-step sintering, which contributed to a high breakdown strength of 580 kV/cm. A recoverable energy storage density of 7.8 J/cm3 and an energy efficiency of 56 % were obtained in 0.90AgNbO 3 -0.10(Bi 0.2 Sr 0.7)TiO 3 ceramics. Moreover, the benign energy storage performance could be maintained at elevated temperatures, variable frequencies and cyclings up to 105. These results demonstrate the great potential of AgNbO 3 -based ceramics for energy storage applications. [ABSTRACT FROM AUTHOR]

High‐capacity vanadium‐based oxides are one kind of promising energy storage materials, especially for electric vehicles. It has become a hot research issue to synthesize vanadium‐based oxides from low‐dimensional nanostructures to 3D micro/nano‐structures and free‐standing‐electrodes. It will become a very attractive and practical strategy in the future to fabricate the “vanadium oxides‐based cathode/solid electrolyte/Li metal anode‐type” all solid‐state secondary‐ion batteries. This is reported by Pengcheng Liu, Kongjun Zhu, and co‐workers in article number 1700547. [ABSTRACT FROM AUTHOR]

Polymer-based dielectric composite films with large energy density are urgently demanded for various applications. Compared with the ones with inorganic fillers, polymer blends exhibit the advantage of mechanical matching as well as the interfacial compatibility. Herein, poly(vinylidene fluoride) (PVDF) composite films with various volume fractions of methyl methacrylate-butadiene-styrene (MBS) were prepared via the solution casting. The maximum energy density of 6.4 J/cm3 at 390 MV/m was obtained by optimizing the content of 12 vol% MBS in MBS/PVDF composite films. The energy density of the optimized composite films was further improved with the help of post-treatments including quenching and/or hot-pressing. At last, the composite films display the enhanced energy density of 8.7 J/cm3 at 500 MV/m with the efficiency of 67.4% via the comprehensive post-treatments. This work provides a paradigm to improve the energy storage performance of PVDF-based composite films for dielectric electrostatic capacitors. [ABSTRACT FROM AUTHOR]

AgNbO 3 -based ceramics have been the spotlight for the lead-free dielectric capacitors due to its unique antiferroelectric feature and the ever-increasing environmental concerns. Herein, synergic modulation on the energy storage properties of AgNbO 3 -based ceramics was reported, in which the over-stoichiometrical introduction of only 0.10 wt% MnO 2 at the atomic-scale leads to reduced leakage current, P r and enhanced antiferroelectric stability while the SiO 2 coating on the AgNbO 3 particles at the micro-scale greatly inhibits the grain growth, increases the breakdown strength and the electric filed inducing the AFE-FE transitions. As a result, a large recoverable energy density up to 3.34 J/cm3 with efficiency of 60.0% was obtained in 0.10 wt% MnO 2 -doped AgNbO 3 @SiO 2 ceramic, which is 2.3 times larger than that of the pristine AgNbO 3. This work provides a rational approach to synergically modulate the energy storage properties. [ABSTRACT FROM AUTHOR]

Silver niobate AgNbO 3 ceramics have been regarded as a promising lead-free material for energy storage applications. In present work, pure and fine AgNbO 3 powders were successfully fabricated via the hydrothermal method using AgNO 3 as the raw material. It is found that the reaction products show strong dependence on the molar ratio of NH 4 HF 2 :AgNO 3 :Nb 2 O 5 , pH value and reaction time. Pure AgNbO 3 powders were obtained when the process conditions are 3NH 4 HF 2 :2AgNO 3 : x Nb 2 O 5 with x ≤0.85 or y NH 4 HF 2 :2AgNO 3 :1Nb 2 O 5 with y = 4–5, pH = 5 and reaction time t ≥ 10 h. Benefitting from the hydrothermal synthesised AgNbO 3 powders, AgNbO 3 ceramics with fine-grain of ∼3.4 μm were obtained. The fine-grain leads to increased electric breakdown strength E b up to 250 kV/cm, which is the highest among the pure AgNbO 3 ceramics to our best knowledge. The further enhancement in E b and recoverable energy density could be highly anticipated if the antiferroelectric phase could be stabilized. [ABSTRACT FROM AUTHOR]

• Multi-scale synergistic design was proposed in AgNbO 3 -based ceramics. • High E b up to 702 kV/cm was obtained in Bi & Sr doped AgNbO 3 ceramics. • Both antiferroelectric stability and polarization were improved via Bi & Sr doping. • W rec and η reached 7.9 J/cm3 and 75.5 % in Bi & Sr doped AgNbO 3 ceramics. • W rec and η in present work are among the top values of AgNbO 3 -based ceramics. Dielectric capacitors with large power densities are indispensable components in advanced electric and electronic devices. However, the limited energy density and efficiency are challenging and badly restrict their utilization in practice. Here, fine-grains, increased resistivity and activation energy, optimized maximum polarization, and benign relaxation features are simultaneously achieved in AgNbO 3 -based ceramics via a multi-scale synergistic design, combining hydrothermal methods with Bi and Sr doping. As a result, we synergistically realized high breakdown strength of 702 kV/cm, large recoverable energy storage density of 7.9 J/cm3 and benign energy efficiency of 75.5 % in (Ag 0.80 Bi 0.04 Sr 0.04)NbO 3 ceramics. Furthermore, excellent temperature-, frequency-, cycling-stability and ultrahigh discharge energy density of 5.6 J/cm3 were simultaneously achieved in (Ag 0.80 Bi 0.04 Sr 0.04)NbO 3 ceramics, indicating a promising candidate for competitiveness and development in advanced high-power applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon coating layer enhances structural stability of WS 2 /MoS 2 @C/rGO composites. • Hollow WS 2 /MoS 2 @C/rGO microspheres contribute to the infiltration of electrolyte. • WS 2 /MoS 2 @C/rGO composites show notable electrochemical properties in LIB and SIB. In this work, the hollow WS 2 /MoS 2 @carbon microspheres anchored on graphene were successfully fabricated via the versatile solvothermal and hydrothermal methods. The WS 2 /MoS 2 heterostructure can offer a great charge transport driving force by forming a built-in electric field. Moreover, the incorporation of conductive carbon materials from carbon layer and graphene can mitigate the enormous volume variation and pulverization of electrode materials in the cycle process and ensure fast electronic/ionic transfer kinetics. Thus, the hollow WS 2 /MoS 2 @carbon/rGO displays superior rate performance and cycling durability in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). It achieves a excellent capacity of 701.8 mAh g−1 at 1 A g−1 after 550 cycles for LIBs. The WS 2 /MoS 2 @carbon/rGO composite displays superior rate capability (320.5 mAh g−1 at 5 A g−1) and cycling durability (411.8 mAh g−1 at 500 mA g−1 after 250 cycles) for SIBs. This work shows a effective strategy for constructing the bimetallic sulfide for energy storage. [ABSTRACT FROM AUTHOR]

• Nd doped BaTiO 3 nanofibers were filled in P(VDF-HFP) via the non-equilibrium process. • Filling ratio, layer number & topological structures were synergistically modulated. • U e of 25.5 J/cm3 with a E b of 719.9 MV/m was achieved with 3.0 wt% filling ratio. • U e of 25.5 J/cm3 is larger than counterparts with the similar filling ratio. • 25.5 J/cm3 is among the top U e values of P(VDF-HFP)-based nanocomposites. Flexible dielectric materials with benign energy storage performance are highly desirable for the miniaturization, portability and integration of modern electronics. However, the limited energy storage density seriously restricts their practical applications. Herein, multilayered composite films composed of the P(VDF-HFP) matrix and Nd doped BaTiO 3 nanofibers with various filling ratios, layer numbers and topological structures were systematically designed and constructed via the layer-by-layer non-equilibrium process. The 3-layered composite films (3.0 wt% filling ratio) with the pure P(VDF-HFP) layer adjacent to the electrodes revealed good mechanical behavior, greatly enhanced captured ions at interfacial regions and suppressed injected charges from electrodes, which facilitated the improvement of the breakdown strength and discharged energy density. And a maximum U e of 25.5 J/cm3 with a E b of 719.9 MV/m was achieved, which was not only 1.4 times more than the pure P(VDF-HFP) via the same process, but also behaved better than counterparts with the similar filling ratios and was among the top U e values of related P(VDF-HFP)-based nanocomposites. [ABSTRACT FROM AUTHOR]