Electrodes For Energy Storage Research Articles

Enhanced performances of NiCoSe2 electrode coated with Ag nanoparticles by magnetron sputtering for the applications of asymmetric supercapacitors

In this work, a binder-free energy-storage electrode material of Ag nanoparticles coated nickel cobalt selenide (NiCoSe2) on Ni foam (NF) was first proposed. Wherein, NiCoSe2 was synthesized by one-step hydrothermal method using ascorbic acid as reductant, and the coating of Ag nanoparticles on NiCoSe2 were performed by magnetron sputtering method. The specific surface area was greatly increased due to the deposited Ag nanoparticles, and in this way the impedance of the electrode decreased, and the electrochemical properties were enhanced. When the magnetron sputtering time is 10 s, Ag/NiCoSe2 electrode exhibits the most excellent performances. However, further increase of sputtering time may result in the over cover on NiCoSe2, with great deterioration in electrochemical behavior. Single NiCoSe2 electrode possesses an area capacitance of 1600.7 mF cm−2 at a current density of 2 mA cm−2, while Ag/NiCoSe2 electrode could reach up to 2280 mF cm−2. The asymmetric supercapacitor (ASC) assembled by Ag/NiCoSe2 and activated carbon (AC) electrodes shows a high energy density of 0.171 mWh cm−2 as well as a power density of 17.340 mW cm−2, and the cyclic stability remains at 90.1% after 4000 cycles, which is superior to 83.7% of the NiCoSe2 single electrode.

Harnessing enhanced lithium-ion storage in self-assembled organic nanowires for batteries and metal-ion supercapacitors

Organic materials are emerging as highly efficient, green and sustainable electrodes for electrochemical energy storage, however with often limited ion storage properties. In this study, we showcase that mesoscale engineering can dramatically...

Solvent-free synthesis of organic electrodes for green sustainable energy storage

The five types of solvent-free synthesis and applications in various fields of energy storage for organic electrodes.

Coaxial nickel cobalt selenide/nitrogen-doped carbon nanotube array as a three-dimensional self-supported electrode for electrochemical energy storage.

Herein, we propose a one-step urea pyrolysis method for preparing a nitrogen-doped carbon nanotube array grown on carbon fiber paper, which is demonstrated as a three-dimensional scaffold for constructing a nickel cobalt selenide-based coaxial array structure. Thanks to the large surface area, interconnected porous structure, high mass loading, as well as fast electron/ion transport pathway of the coaxial array structure, the nickel cobalt selenide/nitrogen-doped carbon nanotube electrode exhibits over 7 times higher areal capacity than that directly grown on carbon fiber paper, and better rate capability. The cell assembled by a nickel cobalt selenide/nitrogen-doped carbon nanotube positive electrode and an iron oxyhydroxide/nitrogen-doped carbon nanotube negative electrode delivers a volumetric capacity of up to 22.5 C cm-3 (6.2 mA h cm-3) at 4 mA cm-2 and retains around 86% of the initial capacity even after 10 000 cycles at 10 mA cm-2. A volumetric energy density of up to 4.9 mW h cm-3 and a maximum power density of 208.1 mW cm-3 are achieved, and is comparable to, if not better than, those of similar energy storage devices reported previously.

Unveiling the effect of growth time on bifunctional layered hydroxide electrodes for high-performance energy storage and green energy conversion

Tailoring the properties of transition metal-based layered double hydroxides is inevitable for high-performance energy storage and efficient urea-electro-oxidation reaction (UOR) for effectively harnessing energy from urea-rich wastewater.

Conductive 2D dithiolene MOF-based electrodes for low-temperature high-performance energy storage

Two hierarchical porous conductive MOF-based electrodes show high capacitance retention when working at −60 °C. This represents an unprecedented MOF electrode material used in the field of low-temperature energy storage.

Biomass-derived B/N/P co-doped porous carbons as bifunctional materials for supercapacitors and sodium-ion batteries

B/N/P co-doped biomass carbons with optimized pore structure and electrical conductivity exhibited supervisor electrochemical performance in supercapacitors and sodium-ion batteries.

New frontiers in alkali metal insertion into carbon electrodes for energy storage.

With rising interest in new electrodes for next-generation batteries, carbon materials remain as top competitors with their reliable performance, low-cost, low voltage reactions, and diverse tunability. Depending on carbon's structure, it can attain high cyclability as with Li+ at crystalline graphite or exceptional capacities with Na+ at amorphous, porous hard carbons. In this review, we discuss key results and research directions using carbon electrodes for alkali ion storage. We start the first section with hard carbon (HC), a leading material of interest for next-generation Na-ion batteries. Methods for tuning the HC structure towards a high capacity pore-filling mechanism are examined. The rate performance of hard carbon electrodes is further discussed. We finish this section with soft carbons that mostly remain as low performing materials compared to other carbons. In the second section, we discuss alkali ion insertion into graphite and graphite-like materials. Though graphite has a long history with Li-ion batteries, it also shows promising characteristics for K-ion batteries. We discuss the significant progress made on improving the electrolyte for high cyclability of graphite with K+. Thereafter, we evaluate B/C/N materials that have a similar structure to graphite but can attain higher capacities for both Li+ and Na+. Finally, we touch on the recent developments using alternative solvents for Na+ cointercalation at graphite and deeper knowledge on the intercalant structure. Despite steady progress, carbon electrodes continue to improve as a key group of materials for alkali energy storage.

High capacitive pt and NiOx loaded supercapacitors with commercial and green synthesized carbon-based materials

Supercapacitors have gained great interest due to their high-power energy density, suitability for clean energy and energy storage applications. In this study, we used commercial multi-walled carbon nanotube (MWCNT), polypyrrole (PPy) and synthesized porous carbon (PC) from Astragalus brachycalyx plant as supporting materials to prepare Pt-NiOx/PPy-MWCNT and Pt-NiOx/PC electrodes by a straightforward method and tested their electrochemical properties for supercapacitor applications. X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were employed to characterize synthesized electrodes. The XRD results confirmed the composition and crystalline structure of related materials in the Pt-NiOx/PPy-MWCNT and Pt-NiOx/PC electrodes. While the MWCNT supporting materials with PPy exhibited filled rod like structure, PC supporting materials showed porous surfaces according to SEM images. The EDS analysis approved chemical composition of the Pt-NiOx/PPy-MWCNT and Pt-NiOx/PC depending on their ingredients. Cyclic voltammetry (CV) measurements were used to characterize capacitor behaviors of the electrode materials in a Swagelok-type cell. The Pt-NiOx/PPy-MWCNT and Pt-NiOx/PC materials displayed 252.36 F/g and 390.97 F/g capacitance values, respectively. The electrochemical experiments revealed that the synthesized materials can be used as energy storage electrode materials for supercapacitor applications.

A facile and scalable fabrication method of scrolled graphene/boron nitride-based van der Waals superlattice heterostructure materials for highly stable supercapacitor electrode application.

Due to the increasing demand for the development of efficient renewable energy supply systems to reduce the mismatch between energy demand and utilization, supercapacitors have attracted increasing attention in the energy industry. However, the development of energy storage electrode materials to be applied at the industrial level is still challenging due to the unsatisfactory durability and scalable production issues. This study suggested a facile and scalable one-pot fabrication method of using graphene/hexagonal boron nitride (G/BN)-based one-dimensional (1D) van der Waals superlattice heterostructures (vdWSLs) as highly stable electrode materials to enhance the energy storage performance by improving the mesopore volume content, specific surface area, electrical properties, and interfacial interaction between the stacked G/BN layers. The G/BN-based vdWSLs were fabricated by a simple scrolling process through the electromagnetic interaction between the attached magnetic iron oxide nanoparticles (Fe3O4 NPs) on the surface of a G/BN vdW heterostructure (vdWH) and the applied magnetic field. The investigation results demonstrate that the changed morphology of the fabricated G/Fe/BN(NS) strongly affects the fine pore distribution, electrochemical performance, and electrical properties. Consequently, as a synergistic effect of an increased mesopore volume content, specific surface area, and C-B-N heterojunction interfacial area, the fabricated G/Fe/BN(NS) electrode showed a 100% enhancement of specific capacitance (207 F g-1 at 0.5 A g-1) and almost 7 times enhancement of electrical conductivity (800 S cm-1) with a nearly 2.3 times increase of carrier mobility (716 cm2 V-1 s-1) compared to that of the G/Fe/BN electrode. Furthermore, it exhibited outstanding long-term cycling stability with almost 119% capacitance retention even after 100 000 charge-discharge cycles. These results suggest that G/Fe/BN(NS) has tremendous potential as an electrode to fabricate high-performance supercapacitors with excellent cycling stability.

Enhancing Carbon Fiber Properties through Lignin-Cellulose Composites: A Comparative Study of Hardwood Vs. Softwood Lignin Sources

Carbon fibers are integral to a wide range of applications, including automotive, construction, packaging, textiles, and emerging fields such as energy storage electrodes like flexible supercapacitors. However, concerns related to limited availability and environmental impact associated with fossil-based carbon fiber production have sparked growing interest in sustainable alternatives, particularly those derived from lignin and cellulose composites. This conference work presents a comparative analysis of the mechanical properties of lignin-cellulose composite carbon fibers derived from hardwood and softwood lignin sources, elucidating the significant influence of lignin origin on fiber performance.Our study focuses on the advantages and disadvantages of utilizing a composite of hardwood lignin vs. softwood lignin with cellulose in carbon fiber production, comparing these materials to commercially available carbon fibers. We emphasize the mechanical performance of these composite fibers, specifically highlighting the tensile strength and tensile modulus as a key metric. Notably, our results demonstrate that carbon fibers derived from hardwood lignin/cellulose composites exhibit superior mechanical strength compared to those from softwood lignin/cellulose composites. To gain fundamental insights into the reasons behind this mechanical disparity, we employed Raman spectroscopy to analyze the carbon structures within the fibers. Our findings revealed that carbon fibers produced from hardwood lignin exhibited a higher degree of graphitization, helping in achieving of typically desirable pre-graphite turbostractic carbon structures. These structural enhancements significantly contributed to the improved mechanical characteristics observed. In summary, our research underscores the critical importance of lignin source selection in the production of lignin-cellulose composite carbon fibers. The mechanical performance of these fibers is closely linked to the carbon morphology influenced by the lignin source. Therefore, understanding and controlling the lignin source from hardwood or softwood is pivotal for tailoring carbon fiber properties to meet specific application requirements. This study not only advances the knowledge in sustainable carbon fiber production but also offers valuable insights into achieving desirable properties for a wide range of applications, including advanced energy storage systems and structural materials.

Mathematical Model Based on Staircase Structure for Impedance Analysis of Non-Ideal and Non-Uniform Processes in Porous Electrodes

Electrochemical impedance spectroscopy analysis for porous electrodes in energy conversion and storage, described as resistance and capacitance, is widely used to understand their electrochemical processes. These processes include: (i) electronic resistance inside the electrode (R e), (ii) ionic resistance in the electrolyte bulk and inside the porous electrode (R ion), (iii) electrical double layer formation (C dl) and charge transfer resistance at the electrode electrolyte interface (R ct) , and (iv) diffusion for charge compensation.As one of the mathematical models in electrochemical impedance spectroscopy for porous electrodes, a transmission line model is known, in which the pore structure is described as a cylinder geometry.1 We have proposed an analytical method that combines the transmission line model with electrochemical impedance spectroscopy using a symmetric cell,2 and have investigated resistance separation in lithium-ion batteries and its effect on battery performances.3-5 Due to mathematical constraints, the transmission line model is limited to a representation of an ideal, uniform process model. Here we propose a mathematical model based on a network model consisting of a staircase structure for electrochemical impedance spectroscopy at porous electrodes that can describe not only ideal and uniform processes but also non-ideal and non-uniform processes (Fig. 1), and aims to help elucidate their borderline behavior.6 The proposed staircase model (Z SCM) gives a series equivalent circuit consisting of Z 0, which is a series circuit of electrode/electrolyte interface impedance (Z int0) and electronic resistance (R e0), and electrolyte resistance (R ion0) as an initial step without pores (Z SCM0 = R ion(0) + Z 0). The one-step model (Z SCM1) is then given a series equivalent circuit consisting of the parallel circuit of Z SCM0 and Z 1 and the electrolyte resistance R ion(1) in series (Z SCM1 = R ion(1) + (Z SCM0 −1+Z1 −1)−1). The staircase model is calculated by incorporating the 1 prior step (Fig. 2). Thus, the model with n steps (Z SCM(n)) is composed of a series equivalent circuit of the parallel circuit of Z SCM(n−1) and Z n and the electrolyte resistance R ion(n) (Z SCM(n) = R ion(n) + (Z SCM(n−1) −1 +Z n −1)−1).Fig. 3 shows Nyquist plots computed for each input parameter at 50 steps for non-Faradic and Faradic processes in the staircase model. The results are in good agreement with the profiles calculated for the transmission electric model.2 The presentation will further show examples of the calculated results using the staircase model for non-ideal and inhomogeneous processes and discuss the analysis of impedance behavior using real electrodes reflecting non-uniform processes. References R. de Levie, Electrochim. Acta, 9, 1231-1245 (1964). N. Ogihara, S. Kawauchi, C. Okuda, Y. Itou, Y. Takeuchi and Y. Ukyo, J. Electrochem. Soc., 159, A1034-A1039 (2012). N. Ogihara, Y. Itou, T. Sasaki and Y. Takeuchi, J. Phys. Chem. C, 119, 4612-4619 (2015). N. Ogihara, Y. Itou and S. Kawauchi, J. Phys. Chem. Lett., 10, 5013-5018 (2019). Y. Itou, N. Ogihara and S. Kawauchi, J. Phys. Chem. C, 124, 5559-5564 (2020). N. Ogihara and Y. Itou, Phys. Chem. Chem. Phys., 24, 21863-21871 (2022). Figure 1

Sensor Absorbents for Heavy Metal Ions By Low-Cost Functionalization of Porous Carbons

Porous carbons are key materials in electrodes for electrochemical energy storage as well as in water purification. Methods to modify porous carbons to enhance their properties as charge storing or water purification materials have been explored during the past decades [1,2]. The main application fields if porous carbon, water purification and energy storage, are highly cost sensitive. For this reason, there is a need to develop low-cost methods to modify porous carbons. Here, the use of benzoxazine chemistry to modify porous carbons is explored. Benzoxazine chemistry can be considered a protection group strategy for phenols, where the phenols from which the benzoxazines are synthesized, are deprotected upon benzoxazine polymerization. Further, benzoxazine polymerization produces Mannich bridges located near phenol groups, motifs that can be used to capture heavy metal ions. More specifically, in the first step, the porous carbons are partially impregnated with benzoxazine monomers, from melt or solutions to afford powders impregnated far below the liquid saturation level of the particles. That is, the particles retain porosity after the impregnation but still have a dry appearance. After impregnation, the particles are heated over the polymerization temperature of the benzoxazine to afford the porous carbon with immobilized functionalities. As phenols can initiate benzoxazine polymerization and be incorporated in the polymer, this method offers a simple route to produce polymerized and immobilized structure at a carbon interface. Here, results on metal ion absorption and the electrochemical response after exposure are presented for carbons modified by impregnation-polymerization of benzoxazines with or without incorporation of phenols. Inks were manufactured from the modified carbons. The electrochemical characterizations were performed on printed arrays of electrochemical cells on a substrate having dimensions of well plates and intended for automatized testing and where the carbon inks were deposited on the working electrodes. This methodology has a potential of simplifying the development of sensor materials and absorbents and can be automatized and potentially be supported with machine learning schemes. The electrochemical responses of exposure of the modified carbon electrodes to metal salt solutions show that impregnation-polymerization of functional benzoxazine can produce absorbents responding electrochemically to metal ion absorption with a scalable process starting from low-cost materials.

Oxidative Molecular Layer Deposition of Conductive PEDOT Coatings Onto Polymer Sponges to Form Compressible Porous Electrodes

The formation of compressible porous sponge electrodes is appealing to overcome liquid phase diffusion in electrochemical applications including energy storage, water desalination, and electrocatalysis. Previous work has employed wet chemical synthesis to deliver conductive materials into porous polymer sponge supports, but these approaches struggle to produce functional electrodes due to (1) poor electrical connectivity of the conductive network and (2) mechanical rigidity of the foam after coating. In this work we employ oxidative molecular layer deposition (oMLD) via sequential gas-phase exposures of 3,4 ethylenedioxythiophene (EDOT) and molybdenum pentachloride (MoCl5) oxidant to coat polyurethane sponges with electrically-conductive and redox-active poly(3,4 ethylenedioxythiophene) (PEDOT) coatings. We analyze the oMLD deposition on compressible polyurethane sponges and modify the reaction conditions to obtain mechanically compressible and electrically conductive sponges. We specifically identify the importance MoCl5 dose time to enhance the conductivity of the sponges and the importance of EDOT purge time to preserve the mechanical properties of the sponges. This approach produces an electrically conductive PEDOT network within the sponge support with minimal impact on the sponge’s mechanical properties, offering advantages over wet-chemical synthesis approaches. The compressible, conductive sponges we generate have the potential to be used as compressible electrodes for water desalination, energy storage, and electrocatalysis.

Intercalated Redox-Active Anions in Layered Double Hydroxides: Toward New Electrode Designs

Layered Double Hydroxides (LDHs) are a versatile class of 2D materials, which consist of layered di- and trivalent metal cation hydroxides with intercalated anions (1). They are used in many applications including energy storage electrodes, water purification or drug delivery (2, 3).In this new study, Anthraquinone-2-sulfonate (AQS) intercalated in the LDH structure of Mg2Al(OH)6, has been investigated and a charge capacity of 100 mAh g-1 has been measured. However, the dissolution of reduced AQS into the aqueous electrolyte occurs from the first reduction leading to a drastic capacity fade upon cycling.To get around the dissolution issue, we synthesize a new intercalated LDH using ferrocene as the redox active moiety. Electrodes with this new LDH material Mg2Al(OH)6-Fc (Figure 1A) showed more stable cycling when used in combination with aqueous or organic electrolytes. However, the most significant increase in cycle life was achieved by operating this electrode in highly concentrated, highly viscous ionic liquid based electrolytes such as Pyr13TFSI. Over 97 % capacity retention was achieved after 200 cycles with a coulombic efficiency close to 100 % (Figure 1B). The higher stability of redox active anions working at positive redox potentials like ferrocene in the LDH structure is a key parameter to improve cycling ability. Moreover, the limited solubility of the intercalated redox anions into the high concentrated ionic liquid electrolyte is also a key factor for improving cycle life of this new electrode.Figure 1: A) Schematic structure of Mg2Al(OH)6-Fc, C) Improved cycling stability of Mg2Al(OH)6-Fc based electrodes in ionic liquid electrolyte Pyr13TFSI. Figure 1

Integrated High Voltage, Large Capacity, and Long‐Time Cyclic Stability of Lithium Organic Battery Based on a Bipolar‐Type Cathode of Triphenylamine‐Hydrazone COF Material

AbstractCovalent organic frameworks (COFs) are a promising class of electrode materials for lithium‐ion batteries. However, the reported cathodes of COFs typically exhibit low potential and voltage plateaus, which limits their further applications. In this work, a new hydrazone three‐dimensional (3D) COF material with bipolar characteristics, PTB‐DHZ‐COF, is constructed by Schiff base condensation of monomeric PTB with DHZ. The cell with PTB‐DHZ‐COF as the cathode exhibits a wide potential range of 1.2–4.2 V and a discharge voltage plateau of over 3.6 V. PTB‐DHZ‐COFX composites are successfully prepared by compounding PTB‐DHZ‐COF with carbon nanotubes. PTB‐DHZ‐COF40 cells show high specific capacity (114.24 mAh·g−1 at 1000 mA·g−1), excellent cycling capability (86.3% capacity retention after 5000 cycles), and ultra‐high energy density (489 Wh·kg−1 at 50 mA·g−1). This work provides a new strategy for the design of new COF materials and the development of high‐performance organic energy storage electrodes.

Highly porous nanocarbons derived from fluorinated polyimide and metal organic framework for energy storage electrodes

In this study, porous nanocarbon is prepared by hybridizing metal–organic framework (MOF, ZIF-8 in this study) and fluorinated polyimide (fPI) and subsequent carbonization. The resulting nitrogen-doped nanocarbon has a considerable specific surface area as high as 1096 m2 g–1 and is thus utilized as an electrode material for high-performance supercapacitors. Particularly, the porous nanocarbon derived from the sample containing 10 wt% of ZIF-8 to fPI exhibits coexistence of nano- and mesopores, leading to enhanced mass transport and electrolyte ion diffusion across electrodes and high-rate performance at high specific current. It also retains its initial performance even after 4000 charging/discharging cycles and provide large specific energy (10.7 Wh kg−1) and power (5 kW kg−1). The incorporation of MOF with fPI enhances the porosity of porous carbons in terms of charge storage and thus this hybridization concept provides a vital platform for energy storage electrodes.

Core-shell Cu2O@CuS@NiCo layered double hydroxide composites as supercapacitor electrode materials

A facile multi-step strategy was designed to synthesize core-shell Cu2O@CuS @NiCo-LDH (LDH, layered double hydroxide) composites. Initially, the Cu2O@CuS matrix material was synthesized by heat treatment and vulcanization at 25 °C, and subsequently, the desired Cu2O@CuS@NiCo-LDH composites were obtained using a hydrothermal method. A core-shell structure consisting of nanosheets uniformly grown on the cubic surface of the core–shell unit was achieved. The states and properties of nanosheet loading with different ratios of Ni and Co were investigated. and Cu2O@CuS @NiCo-LDH in supercapacitors, and a specific capacitance of 970.5 F g−1 was obtained at 1 A g−1. Density functional theory simulations provided additional confirmation of the beneficial synergistic interaction between Cu2O@CuS and NiCo-LDH. The constructed Cu2O@CuS@NiCo-LDH//activated carbon asymmetric supercapacitor (ASC) also attained an energy density of 53.3 Wh kg−1 at a power density of 820 W kh−1. Additionally, the assembled ASC demonstrated extremely high stability with a capacitance retention of 85.5 % after 25,000 cycles of testing thanks to its distinct structure design. These results indicate that the Cu2O@CuS@NiCo-LDH electrode shows promise for application as an energy-storage electrode material.

Cobalt-Nickel Layered Double Hydroxides on Electrospun MXene for Superior Asymmetric Supercapacitor Electrodes.

Flexible electrodes for energy storage and conversion require a micro-nanomorphology and stable structure. Herein, MXene fibers (MX-CNF) are fabricated by electrospinning, and Co-MOF nanoarrays are prepared on the fibers to form Co-MOF@MX-CNF. Hydrolysis and etching of Co-MOF@MX-CNF in the Ni2+ solution produce cobalt-nickel layered double hydroxide (CoNi-LDH). The CoNi-LDH nanoarrays on the MX-CNF substrate have a large specific surface area and abundant electrochemical active sites, thus ensuring effective exposure of the CoNi-LDH active materials to the electrolyte and efficient pseudocapacitive energy storage and fast reversible redox kinetics for enhanced charging-discharging characteristics. The CoNi-LDH@MX-CNF electrode exhibits a discharge capacity of 996 F g-1 at a current density of 1 A g-1 as well as 78.62% capacitance retention after 3,000 cycles at 10 A g-1. The asymmetric supercapacitor (ASC) comprising the CoNi-LDH@MX-CNF positive electrode and negative activated carbon electrode shows an energy density of 48.4 Wh kg-1 at a power density of 499 W kg-1 and a capacity retention of 78.9% after 3,000 cycles at a current density of 10 A g-1. Density-functional theory calculations reveal the charge density difference and partial density of states of CoNi-LDH@MX-CNF confirming the large potential of the CoNi-LDH@MX-CNF electrode in energy storage applications.

Synthesis and characterization studies of facile CuO:La2O3 nanomaterial and its role as electrode for overall energy storage and energy generation applications

Synthesis and characterization studies of facile CuO:La2O3 nanomaterial and its role as electrode for overall energy storage and energy generation applications