Capacitance Of Electrode Research Articles

Designing nano-heterostructured nickel doped tin sulfide/tin oxide as binder free electrode material for supercapattery

New generation of electrochemical energy storage devices (EESD) such as supercapattery is being intensively studied as it merges the ideal energy density of batteries and optimal power density of supercapacitors in a single device. A multitude of parameters such as the method of electrodes preparation can affect the performance of supercapattery. In this research, nickel doped tin sulfide /tin oxide (SnS@Ni/SnO2) heterostructures were grown directly on the Ni foam and subjected to different calcination temperatures to study their effect on formation, properties, and electrochemical performance through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and electrochemical tests. The optimized SnS@Ni/SnO2 electrode achieved a maximum specific capacity of 319 C g− 1 while activated carbon based capacitive electrode exhibited maximum specific capacitance of 381.19 Fg− 1. Besides, capacitive electrodes for the supercapattery were optimized by incorporating different conductive materials such as acetylene black (AB), carbon nanotubes (CNT) and graphene (GR). Assembling these optimized electrodes with the aid of charge balancing equation, the assembled supercapattery was able to achieve outstanding maximum energy density and power density of 36.04 Wh kg− 1 and 12.48 kW kg− 1 with capacity retention of 91% over 4,000 charge/discharge cycles.

Experimental and theoretical investigation of high-performance green-synthesized NaTiO2/AC nanocomposite as high-capacity electrodes for next-generation sodium-ion capacitors

Experimental and theoretical investigation of high-performance green-synthesized NaTiO2/AC nanocomposite as high-capacity electrodes for next-generation sodium-ion capacitors

One-Step laser induced molybdenum carbide/graphene hybrid electrode for supercapacitor

Transition metal carbides (TMCs) have garnered significant attention in various energy applications owing to their outstanding conductive and electrochemical properties. Despite these advantages, challenges persist in terms of non-toxicity and efficient fabrication methods. In this study, a Mo3C2/laser-induced graphene (LIG) heterostructure was synthesized via one-step CO2 laser induced conversion process. The specific area capacitance of the Mo3C2/LIG hybrid electrode reached 23.5 mF cm−2, which is 2.5 times higher than that of pure Mo3C2 and 9 times greater than pure LIG electrodes. Moreover, the hybrid electrode exhibited robust cycling stability, maintaining 98.4 % of its initial capacitance after 10,000 charge–discharge cycles. Theoretical simulation also revealed superior hydrogen adsorption and high electrical conductivity of the Mo3C2/LIG hybrid electrode. This work presents a promising approach for developing advanced molybdenum carbide-based composites and offers an alternative strategy for enhancing the electrochemical performance of capacitive electrodes.

An Antiferroelectric‐Coated Metal Foam Infiltrated with Liquid Metal as a Dielectric Capacitor

Nickel metal foams serve as both a substrate and bottom electrode for a dielectric capacitor using atomic‐layer deposition (ALD) and a eutectic gallium–indium (EGaIn) liquid metal (LQM) counter electrode. The conformal dielectric has a composition of 6.25% Al–HfO2 in the antiferroelectric phase, confirmed with polarization versus electric field measurements. Liquid EGaIn is pressure‐infiltrated within the coated foams to form the dielectric capacitor. Capacitances up to 4 μF are realized. Calorimetry of the infiltrated capacitor shows a 60 J g−1 latent heat upon melting a frozen EGaIn electrode, suggesting that the phase change can alleviate thermal deviations from pulsed power capacitor operation. Infiltrated capacitors are also shown to survive bending and freeze–thaw cycles. The metal foam–ALD dielectric–LQM capacitor shows a combined set of thermal and electrical properties not available in other classes of capacitors.

Hierarchical nickel phosphide/carbon nanofibers for high performance pseudocapacitors

Nickel phosphide (Ni3P)/Carbon nanofibers (CNFs) with controllable sizes and morphologies are synthesized using micro arc oxidation method combined with thermochemical vapor deposition, with adjustment of different annealing temperatures to control the dimension of CNFs. In this study, we report the in situ formation of transition metal phosphide nanoparticles through the conversion of 1D Ni5TiO7 nanowires. This fabrication strategy ensures the high growth density of CNFs. The initially formed Ni3P nanoparticles boost the catalytic growth of CNFs, which feature a high specific surface area and excellent conductivity. Together with redox electrolyte, the specific capacitance of Ni3P/CNFs based pseudocapacitor (PC) is 114.6 mF cm−2 at a scan rate of 10 mV s−1 and maintains 95.0 % of initial capacity after 10,000 cyclic charging/discharging test. Moreover, such composite based symmetric PCs offer an energy density of as high as 31.6 Wh kg−1 accompanied with a power density of 10.3 kW kg−1. The performance of formed PC devices is comparable to market-available (Li-/Na-) batteries. Therefore, Ni3P/CNFs composite film is a suitable capacitor electrode material for constructing high performance symmetric carbon material based PCs.

Supercapacitor electrodes derived from ultra-high surface area activated carbon spheres synthesized by fluidized activation

This study thoroughly investigated the effects of activation conditions on pore structure development using response surface methodology with a central composite design. The activated carbon sphere (ACS) derived from phenolic formaldehyde resins by carbonization and fluidized activation was examined and characterized. The pore size distribution of ACS samples was all in the microporous and mesoporous scales. ACS with an ultra-high specific surface area of 3142 m2 g−1 and total pore volume of 1.513 cm3 g−1 was successfully obtained at 900 °C for 4 h. Electric double-layer capacitor (EDLC) electrodes derived from ACS with different activation conditions were examined by using cyclic voltammetry and galvanostatic charge/discharge to comprehend the influence of surface area, pore volumes, and the amount of binder on the electrochemical performance. The optimal EDLC electrode was obtained using ACS with the largest specific surface area and pore volume with 5 wt% of binder addition. The specific capacitance was 143.7 F g−1 in a 1 M H2SO4 solution. The cyclical stability of the carbon electrode was also examined under 5000 cycles, and the charge/discharge efficiency remained nearly 100 % without deterioration. This study provides insights into fabricating ultra-high surface area ACS and their potential application as supercapacitors.

Phase change-mediated core-sheath 3D printing of hollow microlattice pseudocapacitive aerogel electrode with favorable electrochemical properties

Channel-interconnected regulation within 3D-printed pseudocapacitive electrode architecture to generate high active material loading/utilization and fast ion transport is pivotal but challenging for implementing high-performance pseudocapacitance system. Herein, we demonstrated an innovative phase change-mediated core-sheath direct ink writing (DIW) 3D printing strategy for controllably constructing pseudocapacitive hollow-microlattice graphene/NiCo2O4 aerogel (HGNA) electrode, with regular hollow channels in printed filaments and abundant well-interconnected hierarchical pores built by jointing tortuous pseudocapacitive graphene nanosheets. The unique architectural features facilitated highly efficient diffusion and infiltration of substance throughout the entire thick filaments from both “interior-exterior” and “exterior-interior” directions, thereby enabling high-level yet effective loading of active materials as well as unimpeded ion transport across the printed bulk-structured electrode. Kinetics analysis revealed that the capacitance of pseudocapacitive HGNA electrode was primarily contributed from fast kinetic process. An asymmetric device assembled with DIW-printed HGNA electrode boasted a high energy storage performance with capacitance of 3.43 F cm−2 and energy density of 1.01 mWh cm−2, while featuring remarkable cycling stability (87% after 8000 cycles) and superior capacity even at large electrode thickness. This work opens a promising route for processing rational pseudocapacitive electrode architectures toward high-capacity, fast-kinetics devices.

Surface chemo-mechanics coupling of MnO2/Au layered composites under electrochemical environment

The intersection of surface mechanics and electrochemistry has gradually become a prominent topic in the realm of new energy research. To explore the influence of the electrochemical process on the stress of energy storage electrode composite, supercapacitor material manganese dioxide (MnO2) was selected as the coating and the MnO2/Au composites were prepared by the electrochemical deposition. The surface stress of MnO2/Au composites under different electrochemical modes and the stress variation law of MnO2 with varying thicknesses were determined. The addition of MnO2 could alter the stress response and the strain magnitude of the gold electrode with varied electrochemical potential. The reversible tensile strain within the Au surface during 0.3 ∼ 0.8 V charging was induced by the absorption of SO42−, while the compressive strain of the MnO2/Au composites was related to the extraction of Na+ ions resulting from the redox pseudocapacitance of MnO2. Notably, the produced stress exhibited a linear correlation with the capacitance. And the long-cycle tests revealed that as the specific capacitance of electrodes decreased, the induced tensile stress progressively diminished. This study emphasized the surface chemo-mechanics coupling of both the Au layer and MnO2/Au composites, which would provide a new approach to regulating surface strain in the solid–liquid interface.

Fabrication of asymmetric supercapacitors by laser processing of activated carbon-based electrodes produced from rice husk waste

The development of supercapacitors (SCs) by using carbon electrodes obtained from biomass waste simultaneously promotes the optimized use of the renewable energy by its high-powered storage, and the reduction of contamination in nature. Such industrial sector would be an excellent opportunity also for the developing nations, promoting their economic growth by the conversion of biowaste into added value goods. However, such carbon may not reach the desired performance for SCs. In this work, we used laser processing technology for enhancing the capacitance of SC electrodes composed of activated carbon obtained from rice husk produced in Nigerian farmlands. The activated carbon powder was synthesized by conventional carbonization-chemical activation processes and treated with microwaves. Afterwards, the CO2 laser processing of thin film electrodes composed of a mixture of the carbon powder with carbon black (conductive additive), and precursors as urea (for doping of the activated carbon with nitrogen), or manganese nitrate (for the crystallization of pseudocapacitive Mn3O4 nanoparticles on the carbon surface) was carried out for obtaining enhanced positrodes and negatrodes. The resulting hybrid electrodes exhibited a 3-fold increase of the capacitance (up to 134 F/g @ 10 mV/s) as compared to the raw carbon in the [0, 0.8] V potential window. Asymmetric SC devices integrated by carbon (-)//carbon-Mn3O4 (+) laser-treated electrodes, operating at 1.2 V voltage, revealed up to 300 × higher energy and power densities than symmetric SCs composed of raw carbon electrodes.

Operando tracking of ion population changes in the EDL electrode of a lithium-ion capacitor during its charge/discharge

This study elucidates in-pore ion population changes in an activated carbon (AC)-based electrode operating within an extended potential range, akin to the positive electrode of a lithium-ion capacitor (LIC). Molecular dynamics (MD) simulations applied to a battery-type electrolyte (1 mol L−1 LiPF6 in EC:DMC), both in bulk and adsorbed within a model porous carbon, reveal partial solvation of Li⁺ cations within the pores and complete desolvation of PF6⁻ anions in both states. Operando electrochemical dilatometry (ECD), in situ potentiostatic electrochemical impedance spectroscopy, and operando Raman spectroscopy on AC electrodes confirm: (i) ionic exchange followed by anion adsorption during initial hole injection from the point of zero charge (PZC) to 4.5 V vs. Li/Li⁺; (ii) desorption and peak liberation of trapped PF6⁻ at 3.2 V vs. Li/Li⁺ during hole withdrawal; (iii) perm-selective adsorption of partially solvated Li⁺ during electron injection down to 2.2 V vs. Li/Li⁺; (iv) cation desorption during electron withdrawal up to PZC followed by similar ionic exchange and anion adsorption (as described in (i)) at potentials above the PZC, however with peak liberation of trapped Li⁺ at 3.8 V vs. Li/Li⁺. The high polarization required to extract trapped ions from the pores may explain the reduced lifespan of LICs, requiring further work to eliminate trapping by optimizing porous texture.

Functionalized biobased carbon electrodes for selective phosphorus removal by capacitive deionization: Application and theory study

Capacitive deionization (CDI) emerges as a viable and efficient strategy for the removal and recovery of phosphorus from wastewater. However, the economic feasibility and complex synthesis of current electrode materials restrict its broader industrial application. To overcome the limitation, we fabricated aminated biobased electrode materials (MRSCN) from rice straw, forming active sites and hydrogen bonding interaction interfaces throughout the bulk phase by the nitrogen sites and peripheral amino groups in MRSCN, thereby enhancing the rapid enrichment and selective adsorption of phosphates. The phosphate adsorption capacity of MRSCN electrode reached up to 5.03 mg P/g at 1.2 V. In the presence of competing anions (Cl-, NO3– and SO42-), MRSCN exhibited markedly improved selective adsorption for phosphorus. Furthermore, density functional theory (DFT) calculations revealed that the incorporation of nitrogen active sites optimized the electronic structure of MRSCN. Meanwhile, H2PO4- and HPO42- anions served as hydrogen bond donors to the amino groups, leading to a more robust binding affinity between MRSCN and phosphates relative to other anions. The synergistic interaction between nitrogen sites and amino groups in facilitating selective phosphate removal was validated at the molecular scale. This study demonstrated the considerable potential of modified biobased carbon materials for the application in phosphate removal utilizing the CDI technique.

Hydrothermally etched MXene-based nanocomposite electrode for supercapattery

The requirements of energy storage devices have only been ever-increasing, from greater charge storage to faster charging to boost the energy and power densities. However, existing lithium-ion batteries are limited by their power density due to long charging duration while supercapacitors have limited energy density and higher power density. A supercapattery, a device that possesses the qualities of a battery and a supercapacitor, is being developed to achieve higher energy and power densities in a single device. MXenes are a group of promising materials to be used as electrodes in supercapatteries for their exceptional pseudocapacitive properties. Herein, Ti3C2Tx MXene was synthesized using hydrothermal-assisted etching with various in situ HF etchants, and the effects of using different cationic intercalants were explored. This approach boosts the etching efficiency of weaker etchants, ensuring the proper exfoliation of MXene precursors whilst maintaining the structural integrity of MXenes and removing the need to delaminate and intercalate them post-synthesis. Combined with graphene by sonication, the resulting wrappage of graphene around MXene could increase the electrical conductivity, promote the electrode electrolyte interaction, and improve the electrochemical performance of MXene-based electrode signification and demonstrating synergistic effects. A supercapattery was fabricated by pairing activated carbon as the capacitive electrode and optimized MXene-graphene composite (MG-21) as the pseudocapacitive electrode. The device achieved a specific capacitance of 662.02F/g and an energy density of 20.58 Wh kg−1 at 3 A/g and exhibited an excellent energy and power density of 23.02 Wh kg−1 at 0.5 A/g and 13.1 kW kg−1 at 10 A/g, respectively.

Design of eddy current and capacitance dual-mode sensor for thickness detection of thermal barrier coatings

Abstract Thermal barrier coatings (TBCs) can markedly enhance the service temperature of high-temperature alloys, thereby enhancing the engine thrust-to-weight ratio. However, TBCs must be capable of withstanding a multitude of harsh environments, including high temperatures, high pressures, and high-speed particle impacts, which can potentially lead to damage and failure. Consequently, nondestructive testing of TBCs is of particular importance for the assessment of structural health. As eddy current detection is applicable to conductive materials and capacitive detection is applicable to non-conductive materials, this paper proposes a novel, eddy current/capacitance detection, dual-mode sensor, which combines the advantages of the two detection modes. This study examines the structural configuration and excitation characteristics of the eddy current and capacitance dual-mode sensor. Furthermore, the interaction between the capacitive electrode and the eddy current coil is examined, and the viability of the dual-mode sensor is demonstrated through experimentation. The experimental results demonstrate that the dual-mode sensor exhibits a sensitivity of 2.67 mΩ mm−1 for bond coating thickness detection in eddy current mode with an excitation frequency of 5 MHz, and a maximum sensitivity of 80.31 pF mm−1 for top coating thickness detection in capacitive mode.

Overcoming the Energy vs Power Dilemma in Commercial Li-Ion Batteries via Sparse Channel Engineering.

Improvements in both the power and energy density of lithium-ion batteries (LIBs) will enable longer driving distances and shorter charging times for electric vehicles (EVs). The use of thicker and denser electrodes reduces LIB manufacturing costs and increases energy density characteristics at the expense of much slower Li-ion diffusion, higher ionic resistance, reduced charging rate, and lower stability. Contrary to common intuition, we unexpectedly discovered that removing a tiny amount of material (<0.4 vol %) from the commercial electrodes in the form of sparsely patterned conical pores greatly improves LIB rate performance. Our research revealed that upon commercial production of high areal capacity electrodes, a very dense layer forms on the electrode surface, which serves as a bottleneck for Li-ion transport. The formation of sparse conical pore channels overcomes such a limitation, and the facilitated ion transport delivers much higher power without reduction in the practically attainable energy. Diffusion and finite element method-based simulations provide deep insights into the fundamentals of ion transport in such electrode designs and corroborate the experimental findings. The reported insights provide a major thrust to redesigning automotive LIB electrodes to produce cheaper, longer driving range EVs that retain fast charging capability.

Co/Cu/C multi-doped VOx composite nanobelts for aqueous asymmetric supercapacitors

VOx, possessing multiple stable oxidation states, demonstrates high theoretical capacity, rendering it a promising candidate for supercapacitor electrodes. However, its practical capacity and cyclic performance are hindered by low electrical conductivity and sluggish diffusion kinetics. Incorporating heteroatoms into transition metal oxides has emerged as an effective approach to mitigate these challenges. Nonetheless, the reported capacities and cyclic stabilities of single-element-doped-VOx as supercapacitor electrodes remain unsatisfactory. Herein, we propose a Co/Cu/C multi-doped VOx composite (VCoCuC) nanobelts, which significantly boosts the specific capacity (5.96 C cm−2/398.6 C g−1 @ 10 mA cm−2) and cycling performance (97.1% of the initial capacity after 2,000 cycles @ 60 mA cm−2) compared to samples with only Co/Cu, Co/C, or Cu/C doping. The possible functions of each doping element are discussed. Additionally, an aqueous asymmetric supercapacitor with VCoCuC as the cathode and conductive carbon cloth (CC) as the anode is assembled to demonstrate the potential application of VCoCuC, which delivers high energy density and excellent cyclic performance. These findings highlight the potential for improving the practical capacity and cyclic performance of VOx electrodes via a multi-doping strategy.

N/NiO-ornated graphitic fiber-engrained micro-carbon beads: Innovative packed bed type capacitive electrodes for microbial fuel cells

Nitrogen-doped nickel oxide-catalyzed carbon nanofiber-decorated micro-activated carbon beads (NiO-N-CNF/ACB) were synthesized through suspension polymerization and employed as capacitive fixed-packed bed electrodes in microbial fuel cell (MFC-) for wastewater treatment and byproduct electricity generation. The capacitive electrode was meticulously designed to manifest enhanced characteristics crucial for MFC applications. The large specific surface area of NiO-N-CNF/ACB offers advantages in terms of catalytic sites and stored charge produced by electrogenic bacteria to form an electrochemical double-layer on the electrode, thereby enhancing power generation. The incorporation of NiO, coupled with graphitic contents, biocompatibility, and the formation of three-dimensional structures, contributes to the excellent performance of the NiO-N-CNF/ACB electrodes. The NiO-N-CNF/ACB electrodes-based MFC operated in batch mode demonstrated an open-circuit potential of 0.8 V, an impressive maximum power density of 2900 mW/m3, and a noteworthy 74 % reduction in chemical oxygen demand. Additionally, the synthesized NiO-N-CNF/ACB exhibited a remarkable specific capacitance 754 F/g and a cumulative total charge of 255 C/g, surpassing the corresponding values for plain NiO-ACB and ACB. This study positions NiO-N-CNF/ACB as a promising capacitive packed bed electrode material, offering enhanced power generation, efficient wastewater treatment, and superior biofilm formation, thereby advancing the potential for sustainable and efficient MFC systems.

Optimization of pore structure and surface chemical properties of activated carbon fiber via liquid-phase stabilization for enhanced supercapacitor performance

Stabilization is a crucial factor influencing both the structure and properties of pitch-based activated carbon fiber (PACF). The traditional air stabilization not only requires a high softening point of precursor but also consumes a considerable amount of time and energy. In this study, liquid-phase stabilization was employed to streamline the preparation process, and its influence on resultant PACF was investigated. The oxidation stabilization process is fully conducted in just 1 h through liquid-phase stabilization. The obtained N-doped pitch-based activated carbon fiber (NPACF) possessed higher specific surface area and higher nitrogen content (3.77 wt%) compared to PACF obtained by air oxidization. The specific capacitance of NPACF electrode attained 325 F/g at 0.5 A/g. The device based on two equal NPACF electrodes exhibited a specific capacitance of 222 F/g at 0.5 A/g, an energy density of 7.6 Wh/kg at 248 W/kg, and excellent cycle stability of 92.0 % after 10,000 cycles.

Scalable Self-Assembly of Composite Nanofibers into High-Energy-Density Li-Ion Battery Electrodes.

The application of nanosized active particles in Li-ion batteries has been the subject of intense investigation, yielding mixed results in terms of overall benefits. While nanoparticles have shown promise in improving rate performance and reducing issues related to cracking, they have also faced criticism due to side reactions, low packing density, and consequent subpar volumetric battery performance. Interesting processes such as self-assembly have been proposed to increase packing density, but these tend to be incompatible with scalable processes such as roll-to-roll coating, which are essential to manufacture electrodes at scale. Addressing these challenges, this research demonstrates the long-range self-assembly of carbon-decorated V2O5 nanofiber cathodes as a model system. These nanorods are closely packed into thick electrode films, exhibiting a high volumetric capacity of 205 mA h cm-3at 0.2 C. This surpasses the volumetric capacity of unaligned V2O5 nanofiber electrodes (82 mA h cm-3) under the same cycling conditions. We also demonstrate that these energy-dense electrodes retain an excellent capacity of up to 190.4 mA h cm-3(<2% loss) over 500 cycles without needing binders. Finally, we demonstrate that the proposed self-assembly process is compatible with roll-to-roll coating. This work contributes to the development of energy-dense coatings for next-generation battery electrodes with high volumetric energy density.

FeSnO3/rGO nanocomposite electrode development for supercapacitor application

The manufacturing of electrode materials that are both highly efficient and cost-effective is crucial for energy storage systems. Because of their remarkable performance, nanocomposite materials are a good choice for creating energy storage systems. And the present study contains the fabrication of FeSnO3 and FeSnO3/rGO nanocomposite by hydrothermal approach. To assess electrochemical behavior of FeSnO3 and FeSnO3/rGO nanocomposite number of analytical tools such as galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) were employed. FeSnO3/rGO nanocomposite demonstrate specific capacitance (Csp) 1342.02 F/g and energy density (Ed) was 88.74 Wh/kg at a power density (Pd) of 345 W/kg at a current density of 1.0 A/g. The charge transfer resistance (Rct) of FeSnO3/rGO nanocomposite was found to be Rct = 0.43 Ω which was determined from Nyquist plot as well as showed cycling stability even after remains 5000th cycles. The addition of rGO increased the specific capacitance as well as surface area rise total number of active sites which allows electrolyte and electrode surface to make ideal connection for quick electrolyte ion diffusion. In accordance with the obtained findings, the FeSnO3/rGO nanocomposite is convincing capacitive electrode material for energy storage devices the future.

Optimizing anode materials for lithium-ion batteries: The role of lithium iron phosphate/graphite composites

ABSTRACT In this study, a novel composite anode material for lithium-ion batteries has been developed, targeting advancements in energy storage technology. The study is centered on integrating various percentages of LiFePO4 known for its high thermal stability and high capacity when used as an anode active material with graphite to increase capacity and thermal durability of anode electrode. This approach has led to the creation of LiFePO4/graphite composite anodes, utilizing a slurry mixing technique to combine the beneficial properties of both materials. Thermogravimetric analysis indicate LiFePO4/graphite’s higher thermal stability than its graphite counterpart, which implies that the addition of LiFePO4 alters the thermal decomposition profile of the anode electrode. Electrochemical assessments show that particularly LiFePO4: graphite = 6:94 wt% composite anode electrode delivers the highest discharge capacity of 437 mAh g−1 with Coulombic efficiency of 95%; the highest discharge capacity of 385 mAh g−1 after 200 cycles at 70 mA g−1 with superior capacity retention and rate performance of 311.5 mAh g−1 at 700 mA g−1 compared to the graphite anode electrode. These findings highlight the potential of the LiFePO4/graphite composite as an anode material in improving lithium-ion battery performance, making it a viable option for future energy storage solutions.