Enhanced Energy Storage Performance Research Articles

Lead-Free Antiferroelectric Silver Niobate Tantalate with High Energy Storage Performance.

Antiferroelectric materials that display double ferroelectric hysteresis loops are receiving increasing attention for their superior energy storage density compared to their ferroelectric counterparts. Despite the good properties obtained in antiferroelectric La-doped Pb(Zr,Ti)O3 -based ceramics, lead-free alternatives are highly desired due to the environmental concerns, and AgNbO3 has been highlighted as a ferrielectric/antiferroelectric perovskite for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm-3 and high thermal stability of the energy storage density (with minimal variation of ≤±5%) over 20-120 °C, can be achieved in Ta-modified AgNbO3 ceramics. It is revealed that the incorporation of Ta to the Nb site can enhance the antiferroelectricity because of the reduced polarizability of B-site cations, which is confirmed by the polarization hysteresis, dielectric tunability, and selected-area electron diffraction measurements. Additionally, Ta addition in AgNbO3 leads to decreased grain size and increased bulk density, increasing the dielectric breakdown strength, up to 240 kV cm-1 versus 175 kV cm-1 for the pure counterpart, together with the enhanced antiferroelectricity, accounting for the high energy storage density.

Mn doping to enhance energy storage performance of lead-free 0.7NBT-0.3ST thin films with weak oxygen vacancies

In this study, we present an effective strategy to enhance energy-storage density by the Mn2+ substitution of Ti4+ into 0.7(Na0.5Bi0.5)TiO3-0.3SrTiO3 (0.7NBT-0.3ST) relaxor ferroelectric thin films. The influence of Mn doping on the microstructures, ferroelectric properties, and energy-storage performances of the as-prepared films was investigated in detail. The results show that the values of electric break-down field strength and the difference values between maximum polarization and remnant polarization of the thin films are markedly improved by appropriate Mn doping. Owing to the high break-down field strength of 1894 kV/cm and the huge difference value between the maximum polarization and the remnant polarization of 56 μC/cm2, a giant recoverable energy-storage density of 27 J/cm3 was obtained for the 1 mol. % Mn-doped 0.7NBT-0.3ST thin film. These results indicate that the appropriately Mn-doped 0.7NBT-0.3ST thin films are promising for the application of advanced capacitors with high-energy storage density.

Enhanced energy storage performance of Ba 0.4 Sr 0.6 TiO 3 ceramics: Influence of sintering atmosphere

Abstract Ba0.4Sr0.6TiO3 (BST) powders were prepared by hydrothermal method, the ceramics were sintered in N2, air and O2 atmosphere respectively. The effect of sintering atmosphere on the microstructure, dielectric properties, and energy storage performance of BST ceramics were investigated. The grain size of the BST ceramics sintered in O2 atmosphere was reduced to 0.44 µm, indicating the grain growth was significantly inhibited with increasing oxygen partial pressure due to the lack of oxygen vacancy. Dielectric relaxation behavior was observed in the BST ceramics, and the degree of which was increased with increasing oxygen partial pressure. BST ceramics sintered in O2 atmosphere showed the largest critical breakdown strength of 16.72 kV/mm, at which the highest energy storage density of 1.081 J/cm3 and a moderate energy storage efficiency of (73.78%) were obtained. The dependence of energy-storage properties on applied field was also investigated, it was found that the energy storage density increased with increasing applied filed while the energy storage efficiency decreased with increasing applied filed.

Porous nickel-cobalt layered double hydroxide nanoflake array derived from ZIF-L-Co nanoflake array for battery-type electrodes with enhanced energy storage performance

In view of the complicated synthesis procedures of metallic layered double hydroxides (LDHs) in general preparation, we here report a facile route for synthesizing porous nickel-cobalt layered double hydroxide nanoflake array (Ni-Co LDH-NFA) on nickel foam on the base of our previously reported leaf-like Co-containing zeolitic imidazolate framworks (ZIF-L-Co). The ZIF-L-Co nanoflake array (ZIF-NFA) is first grown on nickel foam, which serves as a sacrificial template to synthesize Ni-Co LDH-NFA when it reacts with nickel nitrate at room temperature. The as-prepared Ni-Co LDH-NFA could be directly used as battery-type electrodes without polymer binder. Due to the highly ordered layered crystal structure of LDH and the well-defined porous nanostructure of nanoflake array, such Ni-Co LDH-NFA electrode exhibits outstanding specific capacity of 894Cg−1 at a current density of 2Ag−1. In addition, an assembled asymmetric supercapacitor device also exhibits excellent specific energy density of 48.6Whkg−1 at a specific power density of 1700Wkg−1. Even at a high power density of 17kWkg−1, the device could still remain an energy density of 18.5Whkg−1.

The synthesis of hollow MoS2 nanospheres assembled by ultrathin nanosheets for an enhanced energy storage performance

Hollow MoS2 nanospheres with enhanced energy storage performance has been synthesized from core–shell ZnS@MoS2 nanostructures.

Spontaneously grown Ni(OH)2on iron oxide nanoparticles with enhanced energy storage performance for electrodes of asymmetric supercapacitors

Spontaneously grown Ni(OH)2over iron oxides for enhanced electrochemical energy storage performance in asymmetric supercapacitors.

Freestanding MoO2/Mo2C imbedded carbon fibers for Li-ion batteries

Flexible and freestanding MoO2/Mo2C imbedded carbon fibers (MoO2/Mo2C ICFs) have been successfully synthesized via an integrated procedure including electrospinning, thermo-plastication in air and reduction/carbonization at high temperature. A series of techniques such as SEM, TEM, N2 adsorption-desorption analysis, XRD, TGA, IR and XPS have been employed to systemically characterize the MoO2/Mo2C ICFs. In particular, it is observed that the MoO2/Mo2C ICFs derived from phosphomolybdic acid have more highly porous structures than those derived from molybdic acid. Most impressively, the obtained MoO2/Mo2C ICFs are directly used as binder- and current collector-free anode materials for LIBs, which exhibit desirable rate capability and satisfactory cycling performance. The electrochemical investigations illustrated that the MoO2/Mo2C ICFs could deliver an initial discharging capacity of 1422.0 mA h g-1 with an original coulombic efficiency of 63.3%, and the subsequent reversible capacity could reach as high as 1103.6 mA h g-1 even after 70 cycles at a current density of 0.1 A g-1. Such a capacity is larger than the theoretical capacity of MoO2 (838 mA h g-1) and pure carbon fibers (460.5 mA h g-1). More importantly, the MoO2/Mo2C ICFs exhibited an excellent rate performance with a capacity of 445.4 mA h g-1 even at a charging current density of 1.6 A g-1. The remarkable enhancement in rate capability and long cycling performance resulted from a synergistic effect between the MoO2 nanoparticles and porous carbon fiber matrix. This methodology can be widely extended to fabricate other metal oxide/carbon composites for significant energy storage and conversion applications.

A facile self-templating synthesis of carbon frameworks with tailored hierarchical porosity for enhanced energy storage performance.

Herein, we present a facile synthesis of hierarchical carbon frameworks with microporous skeletons and interconnected meso/macropores by employing poly(vinylidene chloride-co-methyl acrylate)-b-polystyrene copolymers as precursors. The obtained porosity can be tuned over a broad range via well-selected block proportions of the precursor, enabling its advantageous applications in target-oriented energy storage systems.

Significantly enhanced energy storage performance promoted by ultimate sized ferroelectric BaTiO3 fillers in nanocomposite films

Polymer nanocomposite that consists of dispersed particle fillers and a flexible polymer matrix shows comprehensive excellent dielectric properties and thus is considered as promising dielectric layers in high-performance energy-storage capacitors. However, the commonly employed high permittivity particle fillers cause inevitable dielectric strength deterioration and seriously impede the energy density and reliability of the nanocomposite. To solve this problem, ultimate sized ferroelectric nanofillers, 6.9nm BaTiO3 nanocrystals, are introduced into a poly(vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) polymer matrix to realize both the high dielectric constant and enhanced breakdown strength. The influence of nanoparticle fraction on the microstructure and dielectric properties of the composite films is investigated. Compared to the polymer-ceramic composites with coarse particle fillers, significantly enhanced breakdown strengths (≥330kV/mm) are observed in the nanocomposite films containing 10–40 vol.% BaTiO3 nanofillers. In consequence, a maximal discharged energy density of 9.7J/cm3 is obtained, which confirms that these ultimate sized nanocrystals can perform as superior high permittivity fillers in the nanocomposites for energy storage applications.

Vertically porous nickel thin film supported Mn3O4 for enhanced energy storage performance

Three-dimensionally porous metal materials are often used as the current collectors and support for the active materials of supercapacitors. However, the applications of vertically porous metal materials in supercapacitors are rarely reported, and the effect of vertically porous metal materials on the energy storage performance of supported metal oxides is not explored. To this end, the Mn3O4-vertically porous nickel (VPN) electrodes are fabricated via a template-free method. The Mn3O4-VPN electrode shows much higher volumetric specific capacitances than that of flat nickel film supported Mn3O4 with the same loading under the same measurement conditions. The volumetric specific capacitance of the vertically porous nickel supported Mn3O4 electrode can reach 533Fcm−3 at the scan rate of 2mVs−1. The fabricated flexible all-solid microsupercapacitor based on the interdigital Mn3O4-VPN electrode has a volumetric specific capacitance of 110Fcm−3 at the current density of 20μAcm−2. The capacitance retention rate of this microsupercapacitor reaches 95% after 5000 cycles under the current density of 20μAcm−2. The vertical pores in the nickel electrode not only fit the micro/nanofabrication process of the Mn3O4-VPN electrode, but also play an important role in enhancing the capacitive performances of supported Mn3O4 particles.

Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures.

Lead-free AgNbO3 anti-ferroelectric ceramics with an enhanced energy storage performance using MnO2 modification

Enhanced anti-ferroelectric properties and high recoverable energy densities from 2.5–2.9 J cm−3 were achieved in 0.1 wt% Mn-doped AgNbO3 ceramics over 20–180 °C.

Plasma surface functionalization induces nanostructuring and nitrogen-doping in carbon cloth with enhanced energy storage performance

N2 plasma induces simultaneous nanoporosity and N-doping in carbon cloth, making it an active electrode for supercapacitors, batteries and probably electrocatalysts.

A synergistic effect between layer surface configurations and K ions of potassium vanadate nanowires for enhanced energy storage performance

In this work, the origin of enhanced electrochemical performance of potassium vanadates was investigated.

Enhanced energy storage performance of glass added 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ferroelectric ceramics

In the present work, lead-free ferroelectric 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 (BNT-BT-ST) bulk ceramics with 3BaO-3TiO2-B2O3 (BTBO) glass additive were fabricated by conventional solid state reaction route. The effect of glass content on microstructure and energy storage properties of BNT-BT-ST ceramics was investigated. The maximum energy storage of ∼203 kJ/m3 was achieved for BNT-BT-ST ceramic with addition of 4 wt.% glass. The 4 wt.% glass addition improves energy storage density and energy storage efficiency by ∼15% and ∼52% higher than that of the pure BNT-BT-ST, respectively. The effect of temperature on the energy storage was also estimated. It was observed the temperature has similar effect on energy storage improvement in all compositions. The energy storage density (U) dependent scaling behavior on remnant polarization (Pr), maximum polarization (Pmax), electric field (E) and temperature (T) was also studied. The results of this study are expected to largely benefit the field of ferroelectric based capacitors in discerning the dependency of U on hysteresis parameters (Pr, Pmax, and E) and T.

High-Throughput of Polymer Derived Carbon Nanopillar Arrays for Enhanced Energy Storage Performance

ABSTRACTPolyacrylonitrile (PAN) was printed into a nanostructured carbon nanopillar arrays using a quick, simple, and highly efficient method called spin-on nanoprinting (SNAP). The mold used to print PAN nanostructures could easily be reproduced via printing an inverse replica of carbon nanopillar arrays. The as-printed carbon nanopillar arrays were further prepared as supercapacitor electrodes. As a result, these nanostructured carbon electrodes display an order of magnitude enhancement in specific capacitance compared to non-nanostructured carbon electrodes.

Enhanced energy storage performance in (Pb0.858Ba0.1La0.02Y0.008)(Zr0.65Sn0.3Ti0.05)O3–(Pb0.97La0.02)(Zr0.9Sn0.05Ti0.05)O3 anti-ferroelectric composite ceramics by Spark Plasma Sintering

Anti-ferroelectric composite ceramics of (Pb0.858Ba0.1La0.02Y0.008)(Zr0.65Sn0.3Ti0.05)O3–(Pb0.97La0.02)(Zr0.9Sn0.05Ti0.05)O3 (PBLYZST–PLZST) have been fabricated by Spark Plasma Sintering (SPS) method. The effect of SPS process on phase structure, anti-ferroelectric and energy storage properties of the composites has been investigated in detail. The X-ray diffraction, field emission scanning electron microscopy and energy-dispersive spectrometry analysis illustrate that the composites are composed of tetragonal perovskite, orthorhombic perovskite and small amount of non-functional pyrochlore phases. Compared with conventional solid-state sintering (CS) process, SPS process is helpful to suppress the diffusion behavior between the tetragonal PBLYZST and orthorhombic PLZST phases, and thereby improve the contribution of PLZST phase to the FE-to-AFE phase transition electric field (EA) of the composites. As a result, the SPS composite ceramics possess a considerable EA of 162kV/cm and a high recoverable energy storage density valued 6.40J/cm3 which is 1.75J/cm3 higher than that of the CS samples and about 2.3 times as that of the PBLYZST ceramics.

Nanowire Templated Semihollow Bicontinuous Graphene Scrolls: Designed Construction, Mechanism, and Enhanced Energy Storage Performance

Graphene scrolls have been widely investigated for applications in electronics, sensors, energy storage, etc. However, graphene scrolls with tens of micrometers in length and with other materials in their cavities have not been obtained. Here nanowire templated semihollow bicontinuous graphene scroll architecture is designed and constructed through "oriented assembly" and "self-scroll" strategy. These obtained nanowire templated graphene scrolls can achieve over 30 μm in length with interior cavities between the nanowire and scroll. It is demonstrated through experiments and molecular dynamic simulations that the semihollow bicontinuous structure construction processes depend on the systemic energy, the curvature of nanowires, and the reaction time. Lithium batteries based on V3O7 nanowire templated graphene scrolls (VGSs) exhibit an optimal performance with specific capacity of 321 mAh/g at 100 mA/g and 87.3% capacity retention after 400 cycles at 2000 mA/g. The VGS also shows a high conductivity of 1056 S/m and high capacity of 162 mAh/g at a large density of 3000 mA/g with only 5 wt % graphene added which are 27 and 4.5 times as high as those of V3O7 nanowires, respectively. A supercapacitor made of MnO2 nanowire templated graphene scrolls (MGSs) also shows a high capacity of 317 F/g at 1A/g, which is over 1.5 times than that of MnO2 nanowires without graphene scrolls. These excellent energy storage capacities and cycling performance are attributed to the unique structure of the nanowire templated graphene scroll, which provides continuous electron and ion transfer channels and space for free volume expansion of nanowires during cycling. This strategy and understanding can be used to synthesize other nanowire templated graphene scroll architectures, which can be extended to other fabrication processes and fields.

A new pattern wind power suppression system based on hybrid energy storage techniques

For the purpose of enhancing the penetration levels of wind power, we must take measures to reduce the uncertainty of wind power generation. On the foundation of the classification on the fluctuation of wind power, this paper proposes an active-parallel hybrid energy storage system (APHESS) for balancing fluctuant wind power. The APHESS consists of a battery, a supercapacitor and two charge–discharge controllers. By the reasonable design on the configuration of APHESS and the energy management rule, the APHESS could obtain the enhanced energy storage performance to smoothen various fluctuation of wind power and reduce the investment and maintenance cost. Furthermore, we develop a double-layer control model for APHESS in this paper, which is equipped with an expert information base. The task for the each layer of control system is simply to search the expert information base in sequence to get proper control algorithm. Therefore, the response time can be reduced when the APHESS participates in the wind power regulation. By the simulation research, we conclude that the configuration of APHESS and the control system design are feasible and that the fluctuant wind power can be suppressed effectively by APHESS. As a result, the APHESS can be widely used in wind farm for the real-time regulation on wind power generation.

An Active-Parallel Hybrid Energy Storage System Applied for Regulating Fluctuant Wind Power

In this paper, the wind power fluctuation is divided into three categories. For the purpose of balancing all kinds of wind power fluctuation to enhance the penetration levels of wind power, we propose an active-parallel hybrid energy storage system (APHESS). The APHESS is composed of a battery, a supercapacitor, and two charge-discharge controllers. By combining the battery with the supercapacitor, the APHESS obtains the enhanced energy storage performance. Therefore, the investment cost can be reduced. By the reasonable design on the operation mode of APHESS, the APHESS can interchange power precisely with the wind power system. Furthermore, the battery and supercapacitor can suppress separately different kinds of wind power fluctuation to make their own energy storage properties fully utilized. The APHESS can be widely used in wind farm for the real-time regulation on wind power