Charge-discharge Capability Research Articles

Novel lead-free ceramic capacitors with high energy density and fast discharge performance

Dielectric capacitors with high energy storage density, good frequency/temperature stability, and fast charge-discharge capability are highly demanded in pulsed power systems. In this work, we design and prepare a novel lead-free 0.88BaTiO3-0.12Bi(Li1/3Zr2/3)O3 (0.12BLZ) relaxor ferroelectric ceramic for dielectric capacitor application. The microstructure, conduction mechanism, dielectric properties, and energy storage behavior of the 0.12BLZ ceramic were systematically studied. The impedance analysis demonstrates that the introduction of BLZ enhances the insulation ability and breakdown strength of the 0.12BLZ ceramic. Meanwhile, the introduction of BLZ can also reduce the polarization nonlinearity of the BaTiO3 matrix due to the weakly coupled relaxor behavior. As a result, ultrahigh energy storage density (Urec) of 3 J/cm3 and efficiency (η) of 93.8% were simultaneously achieved in 0.12BLZ ceramic. The significantly improved Urec was far superior to most of the recently reported lead-free bulk ceramics. Additionally, excellent frequency and temperature stability (variations of Urec less than 15% in different frequencies (1–100 Hz) and temperatures (25–140 °C)) can be also observed. In addition, the 0.12BLZ ceramic presents an ultrahigh current density (Ddis) of 759 A/cm2, a giant power density (Pm) of 37.9 MW/cm3, and a fast discharge time of 80 ns. The pulsed charge-discharge performances of the 0.12BLZ ceramic are obviously better than those of other lead-free ceramics. These results indicate that the 0.12BLZ relaxor ferroelectric may be an excellent candidate material applied for pulsed power systems.

Ceramic Nanoparticle-Decorated Melt-Electrospun PVDF Nanofiber Membrane with Enhanced Performance as a Lithium-Ion Battery Separator.

Designing a composite separator that can withstand high temperature, deliver high capacity, and offer fast charge–discharge capability is imperative for developing a high-performance lithium-ion battery. Here, a series of ceramic nanoparticle-coated nanofiber membranes, including Al2O3/poly(vinylidene fluoride) (PVDF), SiO2/PVDF, and Al2O3/SiO2/PVDF, were prepared by melt-electrospinning and magnetron sputtering deposition. Among all of these composite separators, Al2O3/SiO2/PVDF showed several advantages including excellent thermal stability (no dimensional shrinkage at temperature up to 130 °C and an onset degradation temperature of 445 °C) and superb electrolyte compatibility (340% electrolyte uptake). In addition, the β phase of the fibrous PVDF membrane as well as the presence of polar ceramic nanoparticles on the fiber surface can synergistically improve the ion conductivity to 2.055 mS/cm at room temperature, which is more than 8 times higher than that of the commercial polyethylene (PE) separator. Performance of these ceramic nanoparticle-coated separators in a lithium-ion battery demonstrated an improved discharge capacity of 161.5 mAh/g and more than 84.3% capacity retention rate after 100 cycles. The ceramic nanoparticle-coated PVDF separators also maintained 58.4% capacity at a high current density of 8C, which is better than the 49.8% capacity for the commercial PE separator. Therefore, the ceramic nanoparticle-coated PVDF membrane proves to be a promising separator for a high-power and more secure lithium-ion battery.

Mesoporous carbon/Li4Ti5O12 nanoflakes composite anode material lithiated to 0.01 V

A composite anode material is fabricated from mesoporous carbon and synthesized Li4Ti5O12 nanoflakes for application in lithium ion batteries. Li4Ti5O12 is used as a capacity contributing conductive additive because of the change in its electronic structure from insulating to metallic as it undergoes lithiation. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy are used to analyze the electrochemical properties of the mesporous carbon/Li4Ti5O12 nanoflakes composite material, and synergistic results have been confirmed. The composite achieves high specific capacity and excellent cyclability with a capacity stabilizing at 300mAhg−1 after 100 cycles at a current density of 175mAg−1 and 200mAhg−1 after 500 more cycles at a high current density of 500mAg−1. This research shows the applicability of using LTO as a conducting agent with significant capacity contribution as a composite material with anode materials discharged to 0.01V for high energy storage with fast charge–discharge capability.

BaTiO3-Based Multilayers with Outstanding Energy Storage Performance for High Temperature Capacitor Applications

With the ultrahigh power density and fast charge–discharge capability, a dielectric capacitor is an important way to meet the fast increase in the demand for an energy storage system such as pulsed...

Significantly enhanced dielectric breakdown strength and energy density of multilayer ceramic capacitors with high efficiency by electrodes structure design

Multilayer ceramic capacitors (MLCCs) are attracting great interest recently, especially in energy-storage applications due to their high volumetric capacitance, high power density, and fast charge-discharge capability. However, the low dielectric breakdown strength of ferroelectric ceramics always leads to a low discharge energy density, which limits their applications in high-voltage energy-storage systems. In this work, a phase-field electromechanical breakdown model is introduced to give a fundamental understanding of the dielectric breakdown behavior of MLCCs and provide a resource-efficient design strategy for the structure of MLCCs to enhance their dielectric breakdown strength and discharge energy density. Three types of margin lengths of 100 μm, 200 μm, and 400 μm are designed and applied on the MLCCs consisting of ten dielectric layers with the single-layer thickness of 11 μm, to confirm and practice our phase-field breakdown model. A large discharge energy density of 7.8 J cm−3 can be achieved under the applied electric field of 790 kV/cm, together with a high efficiency of 88% in a 400 μm-margin-length MLCC.

Hydrothermal Synthesis and Optical Properties of CuInS2 Micro-/Nanomaterials by Using Gemini Surfactant as Soft Template

We demonstrate in this paper the shape-controlled synthesis of CuInS2 micro-/nanoparticles through a facile hydrothermal method. Samples with different morphologies, i.e., nanoparticles and porous microspheres, are hydrothermally prepared in the presence of Gemini surfactant 1,10-bis(4-methyl-4-hexadecyl piperazine) decamethylene dibromide (Pi-16-10-16) as soft template. The products were characterized by using SEM, XRD, XPS, and EDS. Furthermore, the charge-discharge capability of the as-prepared CuInS2 samples is investigated by using the samples as the cathode in a lithium battery. The charge-discharge cur ves for the cells of CuInS2 exhibit higher initial discharge capacity showing a discharge capacity of 673 mAh/g, which is important for potential applications in photovoltaic (PV) and photoelectrochemical areas.

Synthesis of three-dimensional graphene@Ni(OH)2 nanoflakes on Ni foam by RF magnetron sputtering for application in supercapacitor

Three-dimensional graphene@Ni(OH)2 nanoflake array grown on Ni foam (G/Ni(OH)2/NF) as a binder-free electrode of supercapacitor was prepared by combining a one-step hydrothermal approach and Radio frequency (RF) magnetron sputtering technique. Its electrochemical properties were further investigated by the cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectra. The G/Ni(OH)2/NF showed high specific capacitance (4.0F/cm2 at 1.0 mA/cm2), good rate charge-discharge capability and long cycling stability (ca. 90.6% of its initial value). This work provides a new method to prepare 3D porous electrode materials based on graphene for application in electrochemical energy storage.

Facile preparation of binder–free electrode for electrochemical capacitors based on reduced graphene oxide composite film

Binder-free electrode based on reduced graphene oxide (rGO) is attracting attention for electrochemical capacitors. Here the binder-free electrodes have been fabricated by activating the composite films of GO and carbonized cornstalk-cores. In the composites, the rGO sheets are found to be tightly adhered to the activated bio‑carbon which is intercalated between the rGO sheets to prevent them from stacking. Moreover, the influences of the mass ratios of GO to bio‑carbon on the electrochemical performance have been systematically investigated. The optimal binder-free electrode (rGO/ACCS1/1) prepared from the composite films with 1:1 mass ratio of GO to bio‑carbon exhibits a specific capacitance as high as 278Fg−1 at scan rate of 1mVs−1 and shows excellent stability in 6M KOH electrolyte. Furthermore, the optimal electrode can retain 47.8% of the initial specific capacitance even at current density of 100Ag−1, indicating a fast charge-discharge capability. This work provides a simple method to prepare binder-free composite electrodes by introducing renewable and inexpensive biomass based carbon into activated rGO films.

Hierarchical Porous Activated Carbon Obtained by a Novel Heating‐Rate‐Induced Method for Lithium‐Ion Capacitor

AbstractLithium‐ion capacitor (LIC) is an advanced energy storage system due to the combination of high energy density and rapid charge–discharge capability. However, one of the challenges is to improve the specific capacitance and energy density of cathode at high power density. For activated carbon based cathode, the unique hierarchical porous structure and suitable graphitization are crucial for the improvement of the specific capacitance and energy density. Herein, a novel heating‐rate‐induced method is developed to prepare corncob‐derived activated carbons (C‐ACs) with high electrochemical performances. The as‐obtained C‐ACs possess large surface area (1154 m2 g−1), optimal hierarchical porous structure, and suitable graphitization. Particularly, optimal hierarchical porous structure contains not only the high energy storage of the micropores but also the high‐rate performance of the mesopores and macropores. The optimized C‐ACs‐8 electrode exhibits a specific capacitance of 158 F g−1 at 0.5 A g−1, exciting rate performance, and fast charge transfer capability. A lithium‐ion capacitor device based on C‐ACs‐8 cathode delivers a high energy density of 75 Wh kg−1 at power density of 562 W kg−1 and shows a long cycle life with 86.4% capacitance retention after 1000 cycles.

Fabrication of Hierarchical NiMoO4/NiMoO4 Nanoflowers on Highly Conductive Flexible Nickel Foam Substrate as a Capacitive Electrode Material for Supercapacitors with Enhanced Electrochemical Performance

Hierarchical NiMoO4/NiMoO4 nanoflowers were fabricated on highly conductive flexible nickel foam (NF) substrates using a facile hydrothermal method to achieve rapid charge-discharge ability, high energy density, long cycling lifespan, and higher flexibility for high-performance supercapacitor electrode materials. The synthesized composite electrode material, NF/NiMoO4/NiMoO4 with a nanoball-like NF/NiMoO4 structure on a NiMoO4 surface over a NF substrate, formed a three-dimensional interconnected porous network for high-performance electrodes. The novel NF/NiMoO4/NiMoO4 nanoflowers not only enhanced the large surface area and increased the electrochemical activity, but also provided an enhanced rapid ion diffusion path and reduced the charge transfer resistance of the entire electrode effectively. The NF/NiMoO4/NiMoO4 composite exhibited significantly improved supercapacitor performance in terms of a sustained cycling life, high specific capacitance, rapid charge-discharge capability, high energy density, and good rate capability. Electrochemical analysis of the NF/NiMoO4/NiMoO4 nanoflowers fabricated on the NF substrate revealed ultra-high electrochemical performance with a high specific capacitance of 2121 F g−1 at 12 mA g−1 in a 3 M KOH electrolyte and 98.7% capacitance retention after 3000 cycles at 14 mA g−1. This performance was superior to the NF/NiMoO4 nanoball electrode (1672 F g−1 at 12 mA g−1 and capacitance retention 93.4% cycles). Most importantly, the SC (NF/NiMoO4/NiMoO4) device displayed a maximum energy density of 47.13 W h kg−1, which was significantly higher than that of NF/NiMoO4 (37.1 W h kg−1). Overall, the NF/NiMoO4/NiMoO4 composite is a suitable material for supercapacitor applications.

Carbon-Free TiO2 Microspheres as Anode Materials for Sodium Ion Batteries

In this study, we synthesize a carbon-free anatase/bronze TiO2 microsphere (TiO2(A/B)-MS) via the solvothermal method and demonstrate its potential for use as a high-performance anode material for sodium-ion batteries. The highly compact structure of the microsphere constructed from nanoprimary particles not only enhances the structural stability and subsequently leads to good cycling performance but also enables the transport pathways for Na+ ions and electrons to be shortened, ensuring fast Na-storage performance. In addition, an anatase/bronze interfacial structure of the material further improves fast Na+-ion diffusion kinetics. Benefiting from these merits, the proposed TiO2(A/B)-MS demonstrates a high specific capacity of 221 mAh g–1 at 0.1 C, fast charge–discharge capability up to 50 C, and long-term cycling stability over 1000 cycles at 1 and 10 C without using a conductive carbon matrix. A combination of various experiments and theoretical studies is used to verify the outstanding Na-storage perf...

A small-molecule organic cathode with fast charge–discharge capability for K-ion batteries

PTCDI is initially exploited as a highly efficient organic cathode with impressively fast charge–discharge capability in K-ion batteries.

High energy-storage density of lead-free (Sr1-1.5xBix)Ti0.99Mn0.01O3 thin films induced by Bi3+-VSr dipolar defects.

Capacitors with high energy storage density, low cost, ultrafast charge-discharge capability, and environmental friendliness are in high demand for application in new energy vehicles, modern electrical systems, and high-energy laser weapons. Here, lead-free (Sr1-1.5xBix)Ti0.99Mn0.01O3 (x = 0.01, 0.05, 0.1) thin films grown on Pt/Ti/SiO2/Si substrates were obtained by a sol-gel method. All the thin films have a relatively high dielectric breakdown strength (BDS) due to the added 1% Mn and pinched polarization hysteresis loops can be observed in 5 and 10 mol% Bi-doped SrTiO3 thin films. The ferroelectric behaviors of the Bi-doped SrTiO3 thin films come from the rotation of the TiO6-octahedra induced by the formation of Bi3+-VSr dipolar defects. With the increase of doping concentration, the Pmax-Pr values of the Bi-doped SrTiO3 thin films increased dramatically and can reach 34.3 μC cm-2 upon doping with 10 mol% Bi. A high recoverable energy-storage density of 24.4 J cm-3 with excellent temperature stability was obtained for the 10 mol% Bi-doped ST thin film, which shows that the (Sr0.85Bi0.1)Ti0.99Mn0.01O3 thin film is a promising candidate for high-power energy storage applications. This finding demonstrates an improved energy density of SrTiO3-based thin film systems and a reasonable explanation for the source of the ferroelectricity based on first-principles calculations is given.

Superior charge discharge ability of reduced graphene oxide/Li-ion embedded polymer composite films

Electroactive polymeric composites are recent generation material for energy application in lithium batteries, solar cells and supercapacitors. In present study, reduced graphene oxide is prepared from graphite powder using liquid exfoliation. The synthesized reduced graphene oxide is embedded with polystyrene sulfonic acid/lithium phosphate polymer electrolyte to obtain polymer composite films. The dielectric studies of composite reveals huge change in relaxation time with addition of rGO in polymeric lithium ion composites. This attributes to decrease in ion-dipolar interaction strength and enhanced polymer segmental motion in presence of carbon. It also implies the activation of electrochemical properties of polystyrene sulfonic acid/lithium phosphate/reduced graphene oxide (PL–rGO) composites which can be effectively utilize for charge storage applications. The PL–rGO composite exhibits an improved electrochemical performance with different scan rate on potential window ranged between − 0.5 and 1.2 V. The specific capacitance value of ~ 17 F/g with high rate charge–discharge capability over 8000 cycles was observed. Higher electrochemical stability and steady charge/discharge behavior makes PL–rGO composites a promising candidate for charge storage applications.

Combining high energy efficiency and fast charge-discharge capability in novel BaTiO3-based relaxor ferroelectric ceramic for energy-storage

Compared with the other types of ceramic capacitors, relaxor ferroelectric ceramics demonstrate superior potential in energy-storage fields due to their higher energy efficiency, faster charge-discharge rate, and better temperature stability. In this study, we designed and synthesized a novel high performance BaTiO3-based ((1-x)BaTiO3-xBi(Ni2/3Nb1/3)O3, x = 0.08, 0.10, 0.12, and 0.14) energy-storing ceramics through ferroelectric properties modulation, which display typical relaxor characteristics. The optimum energy storage properties, i.e. ultrahigh energy efficiency (95.9%), high energy-storage density (2.09 J cm−3) and good temperature stability (the fluctuations in energy-storage properties are less than 5% over 20–120 °C) are obtained at x = 0.12 (0.88BT-0.12BNN). The 0.88BT-0.12BNN relaxor ferroelectric ceramic demonstrates obviously superior comprehensive energy-storage properties than most of other unleaded ceramics. Besides, investigation efforts were also spent on the pulsed charge-discharge performance of the 0.88BT-0.12BNN ceramic to evaluate its feasibility as energy-storage devices. More importantly, the 0.88BT-0.12BNN ceramic also exhibits outstanding charge-discharge performance with fast discharge rate (t0.9 < 100 ns), a high level of power density (36.9 MW cm−3), and good temperature stability. These excellent performance parameters qualify this novel and environmentally friendly BaTiO3-based ceramic as a promising alternative option in energy-storage section. Meanwhile, this study also provides an effective approach to attain high energy-storage density as well as energy efficiency in BaTiO3-based relaxor ferroelectric ceramics.

A novel lead-free ceramic with layered structure for high energy storage applications

In recent years, ceramic capacitors have attracted much attention due to their high energy storage properties and fast charge-discharge capability. The (SrTiO3+0.5 wt%Li2CO3)/(0.93Bi0.5Na0.5TiO3-0.07Ba0.94La0.04Zr0.02Ti0.98O3) (STL/(BNT-BLZT)) lead-free ceramic with layered structure was designed and fabricated via the tape-casting and subsequently laminating technique, and sintered by the conventional solid state sintering method in this study. The results reveal that the STL/(BNT-BLZT) multilayer ceramic sintered at 1175 °C with an excellent charge energy density of 3.67 J/cm3 and discharge energy density of 2.72 J/cm3 under 294 kV/cm. In addition, the energy storage properties of STL/(BNT-BLZT) multilayer ceramic also displays good thermal stability from 25 to 100 °C at the electric field of 100 kV/cm. These results indicate that the STL/(BNT-BLZT) multilayer ceramic may be a promising lead-free material for high energy storage applications.

One-step synthesis of porous carbon derived from starch for all-carbon binder-free high-rate supercapacitor

Fast charge–discharge capability even at high current densities is desired for supercapacitors. One-step simple synthesis using sol-gel method is used to fabricate binder-free activated carbon electrode, where KOH was used to tune the porosity of electrode. The gravimetric capacitance of the optimized electrode is up to 272 F g−1 at a current density of 1 A g−1. More importantly, 75.9% gravimetric capacitance retention is kept at an ultrahigh current density of 50 A g−1. Furthermore, a symmetrical supercapacitor device is assembled in 1 M Et4NBF4 in acetonitrile, which delivers an energy density of 18–25 W h kg−1. Apparently, the carbon material with open rich pores provides short ion diffusion pathways for energy storage and the binder-free method guarantees high conductivity of the whole system, leading to high-rate performance. The porous carbon structure as well as the low-cost and simple design paves the way for fabricating supercapacitors with enhanced rate capability.

Interfacial Coupling Effect in Organic/Inorganic Nanocomposites with High Energy Density.

Organic/inorganic nanocomposites (OINs) can be potentially used as high-performance capacitors due to their rapid charge-discharge capability along with respectable power density. The coupling effect of the filler/matrix interface plays a prominent role in the dielectric and electric properties of OINs. Along with a review of contemporary theoretical models, recent advances in interfacial optimization to improve energy density through careful interface control and design are also presented. Possible mechanisms that may improve energy density and potential applications for high-energy-density capacitors are also highlighted.

Poly(diphenanthrenequinone-substituted norbornene) for Long Life and Efficient Lithium Battery Cathodes

Abstract Redox-active polymers with large charge-storage density are candidates for electrode-active materials in next-generation energy storage devices, due to their swift charge-discharge capabilities and their inherent characteristics of redox reactions that occur without significant structural changes, leading to their highly energy-efficient and durable performance. Here we report poly(diphenanthrenequinone-substituted norbornene) (PQN) as a novel class of organic electrode-active material. A Li coin cell composed of the PQN/carbon composite electrode as the cathode exhibited 2.8 V (V vs. Li/Li+) and great cycle performance maintaining a capacity higher than 100 mAh/g for more than 100 cycles at 60 C (i.e. in 1 min charging and discharging). Among many types of o-quinone-containing polymers for Li-ion batteries reported so far, the present research provides the first example of introducing phenanthrenequinone as the pendant group per repeating unit of polymers, which proved to be especially advantageous in terms of robustness and cyclability by virtue of the fused-ring structure to protect the reactive positions of the o-benzoquinone. We also report that the functional group tolerance against many types of redox-active groups, which we have established for the initiator and the propagating end of norbornene derivatives, apply for the phenanthrenequinone-substituted monomer, giving rise to a reversible redox activity.

Designing a High‐Performance Lithium–Sulfur Batteries Based on Layered Double Hydroxides–Carbon Nanotubes Composite Cathode and a Dual‐Functional Graphene–Polypropylene–Al2O3 Separator

AbstractDesigning an optimum cell configuration that can deliver high capacity, fast charge–discharge capability, and good cycle retention is imperative for developing a high‐performance lithium–sulfur battery. Herein, a novel lithium–sulfur cell design is proposed, which consists of sulfur and magnesium–aluminum‐layered double hydroxides (MgAl‐LDH)–carbon nanotubes (CNTs) composite cathode with a modified polymer separator produced by dual side coating approaches (one side: graphene and the other side: aluminum oxides). The composite cathode functions as a combined electrocatalyst and polysulfide scavenger, greatly improving the reaction kinetics and stabilizing the Coulombic efficiency upon cycling. The modified separator enhances further Li+‐ion or electron transport and prevents undesirable contact between the cathode and dendritic lithium on the anode. The proposed lithium–sulfur cell fabricated with the as‐prepared composite cathode and modified separator exhibits a high initial discharge capacity of 1375 mA h g−1 at 0.1 C rate, excellent cycling stability during 200 cycles at 1 C rate, and superior rate capability up to 5 C rate, even with high sulfur loading of 4.0 mg cm−2. In addition, the findings that found in postmortem chracterization of cathode, separator, and Li metal anode from cycled cell help in identifying the reason for its subsequent degradation upon cycling in Li–S cells.