Capacitor Materials Research Articles

Achieving high energy storage density and efficiency in (Na0.5Bi0.5)TiO3-based lead-free ceramics

Due to the demands of miniaturization, weight reduction and green development for electronic devices, development of lead-free dielectric ceramic capacitors with high recoverable energy density (Wrec) and energy storage efficiency (η) attracts much attention. To this end, (1-x)[0.75(Na0.5Bi0.5)TiO3-0.25SrTiO3]-xNdNbO4 (abbreviated as: NBST-xNN) ceramics were fabricated through a solid-state reaction method. After adding NN, the non-perovskite phase of Bi2Ti2O7 (BTO) with low dielectric constant (εr) and loss (tan δ) is generated. Finite element software (COMSOL) was used to explore the influence of the BTO phase on breakdown strength (Eb). The simulation result indicates that the BTO phase with a low εr concentrates a larger local electric field (LEF), and thus weakens the LEF loading in the main perovskite phase, which is beneficial for enhancing Eb. Moreover, NN doping significantly decreases the oxygen vacancy concentration in NBST ceramics, which plays a key role in improving Eb. On the other hand, as NN content increases, the hysteresis of the polarization (P)-electric field (E) loops is substantially suppressed, and the polarization saturation is delayed, which can be ascribed to the appearance of the BTO phase having a linear dielectric characteristic and to the enhanced fluctuations of composition and charge by NN doping. Benefitting from the above factors, the optimal energy storage performance (ESP) with a Wrec of 4.14 J/cm3 and an η of 90 % is obtained in NBST-0.08NN ceramics. Meanwhile, the ESP of NBST-0.08NN ceramics shows good charge-discharge properties and thermal stability. In conclusion, these results demonstrate that NBST-0.08NN ceramics are promising candidates as environment-friendly dielectric capacitor materials.

Boosting the electrochemical properties of MoO3/MnFe2O4/MXene for high-performance supercapacitor applications

The expanding population and extensive usage of energy-consuming sources are the main factors driving the interest of current researchers toward the development of extremely effective and useful electrode materials for high-power energy storage devices. A novel class of 2D transition metal carbides such as MXene has captured significant attention and has distinguished itself from other electrode materials because of its remarkable electrochemical characteristics. In this work, we have fabricated MoO3 and MnFe2O4 via a simple co-precipitation method. Further, we design multifunctional MoO3/MnFe2O4/MXene composite by the combination of MoO3/MnFe2O4 and MXene through the sonication route. SEM results confirmed the fabrication of nanorods of MoO3 and nanoparticles of MnFe2O4, sandwiched within the MXene sheets. As evident from CV profiles, at 10 mVs−1 MoO3/MnFe2O4@MXene showed a higher specific capacitance of 817 Fg−1 than other electrode materials mainly because of the combined effect of MoO3/MnFe2O4 and the conductive nature of MXene sheets. Furthermore, even after 10,000 cycles, MoO3/MnFe2O4/MXene demonstrated outstanding cyclic stability, maintaining 90.2 % retention of its initial specific capacitance. Furthermore, MoO3/MnFe2O4/MXene showed less solution resistance and charge transfer resistance than all other prepared materials. These findings suggest that the MoO3/MnFe2O4/MXene composite is a competent capacitive material in the supercapacitor research area.

Green synthesis of functionalized graphene-based material with dimethyl but-2-ynedioate for electrochemical energy storage devices

Functionalization of graphene with dimethyl acetylenedicarboxylate is achieved through a microwave-assisted Diels-Alder reaction. The physical, chemical, and electrochemical properties of the modified sheets are thoroughly investigated by complementary characterization techniques. Density Functional Theory calculations are employed to examine the functionalization mechanism and to highlight the role of defects such as epoxide bridges introduced in graphene during exfoliation. Our findings provide valuable insights into the development of efficient and cost-effective methods for large-scale production of high-quality graphene-based materials. Specifically, the electrochemical properties of anode materials containing functionalized graphene are evaluated for Li-ion electrochemical energy storage devices, demonstrating excellent electrochemical reversibility and rate capability. The cyclic voltammetry analysis reveals material stabilization after a few cycles, resulting in a coulombic efficiency of up to 95 % and a discharge capacity of 162.3 mA·h·g−1. The galvanostatic cycling test indicates that the material electrode retains 57 % of its initial capacity at a C-rate of 10C, indicating high-power capability. These promising results position organic modified graphene as a potential material for Li-ion capacitors, with a specific capacity that aligns with the last intercalation stage capacity at a lower potential. Overall, the study's findings offer significant contributions to the advancement of graphene-based materials in energy storage applications.

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Enhanced sodium-storage performances of crumpled MXene nanosheets via alkali treatment–induced active ammonium ions

Ti3C2Tx MXene demonstrates excellent potential as an anode material for sodium-ion capacitors. However, the narrow interlayer spacing and self-stacking phenomenon limit its applicability. In this study, we demonstrate an easy two-step method involving freezing and crumpling of MXene nanosheets to improve their Na-ion storage via the addition of ammonium ions (referred to as FCM nanosheets). Flat MXene particles aggregate and undergo folding in an alkaline solution. Ammonium ions can penetrate the gaps between MXene nanosheets, expanding interlayer spaces and inducing the formation of folds. Compared to MXene nanosheets, FCM nanosheets exhibit improved ion transfer kinetics and additional high capacity owing to the intercalated ammonium ions. The manufactured FCM anode exhibits remarkable electrochemical properties, including a high specific capacity of 313 mAhg−1 and stability over 15,000 cycles.

Excellent energy storage properties and multi-scale regulation mechanism of Sr(Zr0.5Ti0.5)O3-(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics

With the rapid advancement of energy storage technologies, dielectric capacitor materials with the outstanding recoverable energy density and power density have garnered significant attention from researchers in the past decades. In this study, (1-x) (Na0.5Bi0.5)0.94Ba0.06TiO3-xSr(Zr0.5Ti0.5)O3 ceramics were prepared via a solid-state reaction method, and the impact of composition on their structure, energy storage performance and stability were investigated. The results revealed that the introduction of Sr(Zr0.5Ti0.5)O3 induced the ferroelectric-relaxor transformation of (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics, leading to the destruction of the long-range ferroelectric order and the formation of polar nanoregions. In addition, the 0.7(Na0.5Bi0.5)0.94Ba0.06TiO3–0.3Sr(Zr0.5Ti0.5)O3 ceramic exhibited the optimal comprehensive energy storage performance: its recoverable energy storage Wrec attained 8.19 J/cm3 at 650 kV/cm, while the energy storage efficiency η was 85.6 %. Meanwhile, it displayed exceptionally high power density (315.7 MW/cm3) and charge-discharge rate (t0.9 = 50.4 ns). Moreover, this ceramic demonstrated the impressive energy storage performance, in particular, good temperature stability across a wide range of temperatures (20–140 °C), frequency stability (1–200 Hz), and fatigue resistance (1–106 cycles). Finite element analysis showed an enhancement in the breakdown field strength of the ceramics was attributed to the reduction in grain size. First-principles calculations revealed that the band gap increased after adding Sr and Zr elements, and the interactions between the states of O 2p and Ti 3d, Zr 3d, Bi 6p may serve as the microscopic origin of electron energy level polarization and enhanced dielectric performance. Thus, the ceramics have great potential for the application in high-power pulsed electronic systems.

Achieving high energy storage performance in PbHfO3-based antiferroelectric ceramics by Sr element doping

Antiferroelectric (AFE) ceramics are the most promising material system for energy storage in dielectric capacitors due to their fast charging-discharging rate, good chemical stability, and high energy storage density. However, it is exceedingly challenging to simultaneously achieve the excellent recoverable energy density (Wre) and high energy storage efficiency (η) at present. In this work, (Pb0.925-xSrxLa0.05)(Hf0.95Ti0.05)O3 AFE ceramics with various Sr contents are fabricated by solid-state sintering processing. It has been found that Sr-doping in the A-site can significantly affect the microstructure, including reducing grain size and modulation period, effectively strengthening the antiferroelectricity, which is responsible for the improved energy storage performance. The high recoverable energy storage density of 10.2 J/cm3 is obtained at 560 kV/cm with an ultra-high efficiency of 93.0% in (Pb0.875Sr0.05La0.05)(Hf0.95Ti0.05)O3 ceramics. These features suggest that Sr-doped PbHfO3-based AFE ceramics can serve as promising candidates for capacitor materials, offering significant potential in the realm of energy storage applications.

Electrochemical potential of chitosan nanoparticles obtained by the reverse micellar process

Chitosan nanoparticles are synthesized by the reverse micellar technique using heptane as solvent and hexamine as surfactant. XRD, FTIR, and SEM/EDAX analyses are performed to investigate the structural and morphological behavior of chitosan nanoparticles. XRD shows the crystalline nature of the materials with peaks appeared at 2θ =17.8 °, 25.5 °, 31.2 °, 36.4 °, 44.7 °, and 48.5 °. The average crystallite size of obtained chitosan nanoparticles is 25 nm. The identification of functional groups in both pure chitosan and chitosan nanoparticles are compared using FTIR analysis. Noticed at wavenumbers 3435 cm−1 and 3460 cm−1 corresponds to the stretching vibration of the –NH2 and –OH functional groups. SEM shows the uniform morphology of the materials and EDAX shows the presence of various elements (carbon, nitrogen, oxygen, aluminum and chlorine) in both the materials. The electrochemical behavior of the nanoparticles was analyzed by cyclic voltammetry analysis and galvanostatic charging/discharging. Electrochemical faradaic performance identifies chitosan nanoparticles as effective electrode materials in pseudo capacitors.

Carbon nanospheres-induced enhanced capacitive dynamics in C/WS2/WO3 nanocomposites for high-performance electrochemical capacitors

This work investigates the impact of carbon nanospheres on the electrochemical performance of C/WS2/WO3 nanocomposites for electrochemical supercapacitors. The nanocomposites have been synthesized and characterized by various techniques like XRD, UV–vis spectroscopy, SEM, TEM and FTIR. The electrochemical properties of the nanocomposites have been analysed in order to study the charge transport, reaction kinetics, impedimetric properties and specific capacitance by using cyclic voltammetry (CV) and potentio electrochemical impedance spectroscopy (PEIS). The capacitive performance of the samples has been investigated by the obtained specific capacitance values and Nyquist plots. The specific capacitance of the samples has been found in a range of 0.8–2.8F/g at 20 mV/s. The sample with the least amount of carbon showed maximum specific capacitance. The electrochemical insights, combined with comprehensive material characterizations, provide valuable knowledge for tailoring the capacitive performance of C/WS2/WO3 nanocomposites through controlled carbon nanospheres and thus the suitability of materials for electrochemical capacitors.

Facile synthesis of MgO-carbon nanocomposites for advanced capacitive electrode materials

Facile synthesis of MgO-carbon nanocomposites for advanced capacitive electrode materials

ZIF-67 MOF-Derived Mn3O4 @ N-Doped C as a Supercapacitor Electrode in Different Alkaline Media.

Transition-metal oxide has been identified as an auspicious material for supercapacitors due to its exceptional capacity. The inadequate electrochemical characteristics, such as prolonged cycle stability, can be ascribed to factors, such as low electrical conductivity, sluggish reaction kinetics, and a deficiency of active sites. The transition-metal oxides derived from the MOF materials offer a larger surface area with enriched active sites and a faster reaction rate along with good electrical conductivity. The manganese (Mn)-based metal-organic framework (MOF)-derived materials were produced using the pyrolysis method. Zeolitic imidazolate frameworks (ZIF-67) were fabricated in water at ambient temperature with the aid of triethylamine. Multiple techniques were used to examine the characteristics of the fabricated electrode materials. The influence of the electrolyte on the electrochemical activity of the Mn3O4@N-doped C electrode materials was determined in KOH, NaOH, and LiOH. For manufacturing of "Mn3O4@N-doped C", ZIF-67 was used as a precursor. The capacitive performance of the Mn3O4@N-doped C electrode increased as a result of nitrogen-doped carbon; after 5000th cycles, the electrode retained an excellent rate capability and a high specific capacitance (Cs) of 980 F g-1 at 1 A g-1 under 2.0 KOH electrolyte in a three electrode system. The carbonized manganese oxide displays also had a high Cs of 686 F g-1 in two electrode systems in 2.0 M KOH. Materials made from MOFs show promise as capacitive materials for applications in energy conversion storage owing to their straightforward synthesis and strong electrochemical performance.

Influence of raw material pretreatment methods on macro responses in BaTiO3–BaZrO3 solid solutions

This research is devoted to studying the influence of mechanoactivation and different thermodynamic prehistory on characteristics that are practically important for the electronic components. The structural and dielectric characteristics, as well as piezoresponse in solid solutions of BaZr x Ti1- x O3 are studied. The impurity composition and texture features have been determined, which have a critical impact on the characteristics of the created piezoelectric and capacitor materials.

Radially oriented Ni3(HITP)2 microspheres as high-performance anode materials for Li-ion capacitors with exceptional energy density and cycling stability

Developing of high-energy, high-power-density energy storage devices is challenging. Despite being promising electrode materials for these devices, metal–organic frameworks (MOFs) have poor electrical conductivity and weak ligand–metal coordination. Here, the highly conductive MOF, Ni3(HITP)2, which comprises radially oriented microspheres, is adopted as the anode for Li-ion capacitors (LICs). The half-cell demonstrates high reversible capacity (834 mAh g−1) at 50 mA g−1 with minimal capacity reduction, attributable to the participation of C and N functional groups of the ligand and Ni2+ in the redox reactions during charge/discharge. Especially, density functional theory calculations show that, apart from the inner rings, participation of the outer rings of Ni3(HITP)2 in the redox reactions is responsible for the high Li + storage capacity. An LIC with a Ni3(HITP)2 anode and commercial activated-carbon cathode demonstrates high specific energy (120.7 Wh kg−1) at 89.2 W kg−1, nearly twice as high as that of graphite-based LICs, and maintains specific energy of 25.8 Wh kg−1 even at high specific power (7.16 kW kg−1), over the range 1–4.4 V, along with high cycling stability (76% capacity retention over 10000 cycles). The proposed radially oriented Ni3(HITP)2 microspheres have potential for application as the anode in high-performance energy storage devices.

GO based nanocomposite hydrogel enabled high performance wearable all-solid supercapacitor based on hierarchical structure electrodes derived from ZIF-67

The flexible and wearable supercapacitors have attracted wide interest because of their widespread application in smart electronic devices with rapid charging and discharging. As an important part of supercapacitor, the electrode materials with a hollow structure, especially those with hierarchical structures that provide an array of continuous hollow cages, are considered promising. Because of its porous shell which is rich in redox reaction sites for supercapacitors. In this work, we fabricated a ZIF-67 derived hollow Co3O4 growth on the surface of 1D NiCo2O4 to assemble into a beaded structure. In this case, NiCo precursor acted as a structure-directing agent to grow a ZIF-67, a promising electroactive material of electrochemical capacitors to provide capacitance after calcination. Combined with the grapheneoxide (GO) based high conductivity hydrogel as the solid electrolyte, the capacitance of the flexible supercapacitor exhibited a high specific capacitance of 90F g−1 at 0.5 A/g, and it was sturdy and durable. There was no significant loss of capacitance while suffering from bending and pressing. The outstanding electrochemical properties of the all-solid supercapacitor can be attributed to the unique nanostructure of the electrode that created more reactive active sites, increased the diffusion pathway for electrolyte ions, along with the high conductivity of the hydrogel electrolyte.

Preparation of polyimide-based activated carbon fibers and their application as the electrode materials of electric double-layer capacitors

Preparation of polyimide-based activated carbon fibers and their application as the electrode materials of electric double-layer capacitors

A Physical Model of Electrode Material for Hybrid Capacitors

A Physical Model of Electrode Material for Hybrid Capacitors

Enhanced energy storage performance of Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics by synergistic optimization strategies

Despite the fact that Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics have attracted widespread interest due to their various advantages, their lower recoverable energy storage density (Wrec) and energy storage efficiency (η) limit their development in pulsed power capacitors. In this work, we propose a synergistic optimization strategy to enhance the energy storage performance of 0.65Na0.5Bi0.5TiO3-0.35SrTiO3(NBST) based lead-free ceramics by introducing Bi0.8La0.2(Ni0.5Zr0.5)O3 (BLNZ) and employing viscous polymer process (VPP). The former converts the macroscopic domains into microscopic domains, limiting the polarization response hysteresis to give a large Pm–Pr. The latter reduces the thickness and porosity of the samples, resulting in a substantial increase in breakdown strength. Ultimately, by stepwise optimization of this strategy, the x = 0.15 ceramic by VPP (0.15VPP) achieves excellent energy storage performance (Wrec = 7.6 J/cm3, η = 92%) under 620 kV/cm and reliable temperature stability from 20-140 °C. The combined excellent results of this study show that our synergistic optimization strategy can effectively enhance the energy storage performance of NBT-based dielectric ceramics and could be further extended to other ceramic materials for pulsed power capacitors.

Confined grotthuss proton-conduction along polyoxometalate chains inside carbon nanotubes for high-rate charge storage

Redox-active materials with excellent rate capability and cycling performance are in highly demand for electrochemical energy storage and conversion applications. Here, we unveil the confined proton-conduction behavior of one-dimensional polyoxometalate chains inside single-walled carbon nanotubes (SWNTs). The polyoxometalate molecules including phosphomolybdic acid {HPMo} and phosphotungstic acid {HPW} are encapsulated within SWNTs via host–guest recognition, driven by the electron transfer from nanotubes to polyoxometalates. Impressively, the redox hybrids of polyoxometalate@SWNTs deliver abnormal rate performance in acidic solution with capacity retentions over 73 % at high sweep rate of 1000 mV s−1, relative to the capacity at 10 mV s−1. This value is comparable to that of the pure SWNTs, typically known as double-layer capacitive materials. Electrochemical analyses reveal the Grotthuss proton-conduction mechanism of {HPMo} in SWNTs with a low activation energy of 0.11 eV. Therefore, the {HPMo}@SWNT hybrid demonstrates quasi diffusion-free characteristic with dominant capacitive contribution over 60 % at different sweep rates. Molecular dynamic simulations and density functional theory calculations evidence the strong burst-like transport of protons in the {HPMo}@SWNT hybrid. This process is dynamically favored in the continuous and long-range hydrogen-bond network along polyoxometalate chains with bound/free water molecules inside SWNTs. The superiority of nanoconfined Grotthuss mechanism may engender an exciting avenue for developing high-performance energy storage materials.

Enhanced energy storage properties of silver niobate antiferroelectric ceramics with A-site Eu3+ substitution and their structural origin

AgNbO3 (AN)-based lead-free antiferroelectric ceramics are widely studied for their use as dielectric capacitor materials. In this study, Eu3+-doped AN ceramics were prepared and the results show that Eu3+ diffused into the AN lattice. The ceramics were formed by M1 and M2 phases coexisting at room temperature, as distinct from the M1 (M: monoclinic) phase of pure AN. Electrical properties and structural characterization showed that the antiferroelectric stability of the ceramics increases with the increase in Eu3+ levels. At room temperature, Ag0.94Eu0.02NbO3 ceramic exhibited a good energy storage density of 5.3 J/cm3 and a high efficiency of 71.9%. When the temperature rises from room temperature to 140 °C, the efficiency of the sample decreases from 80.4% to 67.1% and Wr decreases from 2.1 to 2.0 J/cm3, which indicates that the sample has good temperature stability. The time constant (t0.9) of this sample was less than 60 ns and the power density (PD) was 51.3 MW/cm3, indicating excellent charge–discharge capabilities. This novel ceramic is expected to be used as a new dielectric capacitor material for pulsed power supplies.

Excellent Energy Storage Performance of ZnO doped (Pb,La)(Zr,Sn,Ti)O3 Based Antiferroelectric Ceramics at an Ultra‐Low Sintering Temperature of 940 °C

Abstract(Pb,La)(Zr,Sn,Ti)O3‐based antiferroelectric ceramics have excellent energy storage performance(more than 90% efficiency), which make them have great application advantages in the field of ceramic capacitors. However, the sintering temperature of (Pb,La)(Zr,Sn,Ti)O3‐based antiferroelectric ceramics is generally above 1250 °C, which limits application as a material for ceramic capacitors. Cu inner electrode has a low co‐firing temperature and high conductivity and a low cost price, making it more competitive in the field of ceramic capacitor inner electrode. Therefore, the first step is to reduce the sintering temperature of (Pb,La)(Zr,Sn,Ti)O3‐based ceramics to below 1000 °C(co‐firing temperature with Cu inner electrode), which is the key and difficult point. In this paper, Pb0.94La0.02Sr0.04(Zr0.45Sn0.47Ti0.08)0.995O3(PLSZST) antiferroelectric ceramics are doped with ZnO, which effectively reduce the sintering temperature. Among them, PLSZST‐1 wt% ZnO is sintered at an ultra‐low sintering temperature (TSintering = 940 °C), which is 330 °C lower than that of PLSZST(TSintering = 1270 °C) without doping ZnO. At the same time, PLSZST‐1 wt%ZnO obtain a recoverable energy density of 4.26J cm−3 and an energy efficiency of 95.5% at 230 kV cm−1. The pulse discharge energy density (Wdis = 3.92 J cm−3) and discharge time (t0.9 = 351 ns) are obtained at 220 kV cm−1, and the current density (CD = 1338A cm−2) and power density (PD = 134MW cm−3) are obtained at 200 kV cm−1. The results provide a possible material basis for Cu internal electrode ceramic capacitors.