Modified Graphite Felt Electrode Research Articles

Highly active nitrogen-phosphorus co-doped carbon fiber@graphite felt electrode for high-performance vanadium redox flow battery

Heteroatom-doped electrodes offer promising applications for enhancing the longevity and efficiency of vanadium redox flow battery (VRFB). Herein, we controllably synthesized N, P co-doped graphite fiber electrodes with conductive network structure by introducing protonic acid and combining electrodeposition and high temperature carbonization. H2SO4 and H3PO4 act as auxiliary and dopant, respectively. The synergistic effect between N and P introduces additional defect structures and active sites on the electrodes, thereby enhancing the reaction rate, as confirmed by density functional theory calculations. Furthermore, the conductive network structure of carbon fibers improves electrode-to-electrode connectivity and reduces internal battery resistance. The optimized integration of these strategies enhances VRFB performance significantly. Consequently, the N, P co-doped carbon fiber modified graphite felt electrodes demonstrate remarkably high energy efficiency at 200 mA cm−2, surpassing that of the blank battery by 7.9 %. This integrated approach to in-situ controllable synthesis provides innovative insights for developing high-performance, stable electrodes, thereby contributing to advancements in the field of energy storage.

Amorphous Cobalt Tin Oxide/Reduced Graphene Oxide Decorated on Graphite Felt as Positive Electrode for Vanadium Redox Flow Battery

The Vanadium Redox Flow Battery (VRFB) stands out as one of the most promising large-scale energy storage systems. Nevertheless, the graphite electrode materials commonly used in VRFBs often exhibit drawbacks such as limited electrochemical activity and insufficient conductivity, ultimately resulting in suboptimal performance for the VRFB. In this study, we utilized highly conductive reduced graphene oxide (rGO) as a carrier for cobalt tin oxide (CoSnO3), aiming to enhance their catalytic capability towards vanadium ions. CoSnO3/rGO composite was confirmed using XRD and TEM, revealing nanoboxes morphology and amorphous structure. XPS and EPR analysis showed an increase in oxygen vacancies after composite formation. In order to further prove the effect of CoSnO3/rGO composite catalyst modified graphite felt, the modified graphite felt electrode was applied to the positive electrodes of VRFB, and the charge and discharge tests at different current densities were carried out. At a current density of 160 mA/cm², the composite demonstrated a voltage efficiency of 74.22%, surpassing the heat treated graphite felt by 2.69%. Noteworthy enhancements in capacitance were also evident at this specific current density. Furthermore, stability testing over 50 cycles revealed no significant degradation, underscoring the superior performance and outstanding durability of the CoSnO3-rGO modified graphite felt throughout charge and discharge cycling. The result of this study highlight the promising potential of CoSnO3-rGO composites as efficient catalysts for vanadium redox flow batteries, providing improvements in electrochemical performance and long-term stability.

O vacancy-rich doped WO3/GF as a novel electrode for an aqueous DHAQ/ K4Fe(CN)6 redox flow battery

In this study, a graphite felt (GF) electrode was modified with N and S heteroatoms before being loaded with Ti-doped or Nb-doped WO3 to produce Ti-WO3/GF-N-S and Nb-WO3/GF-N-S electrodes. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to analyze the crystal structure, morphology, and elemental state of the modified GF electrodes and investigate the impact of nonmetallic and metallic element doping. The influence of metal doping on the electronic distribution of the oxide was determined using first-principle calculations. The electrochemical properties of the modified GF were studied using cyclic voltammetry, electrochemical impedance spectroscopy, and single-cell tests. The results showed that Ti or Nb doping changed the energy band structure, bond length, and bond angle in the WO3 crystal and formed O vacancies. The chemical properties of Ti and Nb resulted in different numbers of O vacancies for the two doped-WO3.The doping of N and S heteroatoms on the carbon fibres altered the O vacancy concentration of WO3. The synergism between the two doping methods accelerated electron transfer in the anthraquinone redox reaction. In addition, the N-containing functional groups provide lone-pair electrons, which accelerate electron transfer and anthraquinone adsorption. Therefore, compared to the pristine GF, the discharge capacities of the Ti-WO3/GF-N-S and Nb-h-WO3/GF-N-S graphite GF electrodes increased by 58 % and 41 %, respectively, and the Nb-h-WO3/GF-N-S graphite GF electrodes exhibited a good capacity retention rate. This study broadens the practical applications of aqueous anthraquinone redox flow batteries.

Binder-Free CNT-Modified Excellent Electrodes for All-Vanadium Redox Flow Batteries.

Electrodes are one of the key components that influence the performance of all-vanadium redox flow batteries (VRFBs). A porous graphite felt with modified fiber surfaces that can provide a high specific activation surface is preferred as the electrode of a VRFB. In this study, a simple binder-free approach is developed for preparing stable carbon nanotube modified graphite felt electrodes (CNT-GFs). Heat-treated graphite felt electrodes (H-GFs) are dip-coated using CNT homogeneous solution. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results conclude that CNT-GFs have less resistance, better reaction currents, and reversibility as compared to H-GF. Cell performances showed that CNT-GFs significantly improve the performance of a VRFB, especially for the CNT-GF served in the positive side of the VRFB. CNT presence increases the electrochemical properties of the graphite electrode; as a result, reaction kinetics for both VO2+/VO2+ and V3+/V2+ are improved. Positive CNT-GF (P-CNT-GF) configured VRFB exhibits voltage efficiency, coulombic efficiency, and energy efficiency of 85%, 97%, and 82%, respectively, at the operating current density of 100 mA cm-2. At high current density of 200 mA cm-2, the VRFB with P-CNT-GF shows 73%, 98%, and 72% of the voltage, coulombic, and energy efficiencies, respectively. The energy efficiency of the CNT-GF is 6% higher when compared with that of B-H-GF. The VRFB with CNT-GF can provide stable performance for 300 cycles at 200 mA cm-2.

Surface-modified graphite felt incorporating synergistic effects of TiO2 decoration, nitrogen doping, and porous structure for high-performance vanadium redox flow batteries

Construction of porous surface, decoration of metal oxide, and introduction of defects are three major strategies to improve the electrocatalytic capability of graphite felt (GF) for vanadium redox flow battery (VRFB). In this study, we have successfully achieved the urea-assisted deposition of TiO2 onto GF, resulting in a synergistic effect that realizes the three modifications mentioned above, through a facile one-pot approach. During the post-annealing process, the decorated TiO2 can further undergo carbon-thermal reduction to etch the GF surface, leading to a porous surface. Additionally, the defective structures such as oxygen defects and nitrogen doping also be can simultaneously incorporated in the modified GF. As a result, the modified GF shows a dramatically improved electrocatalytic capability towards the VO2+/VO2+ redox reactions due to better hydrophilicity, larger surface area, and numerous oxygen defects. The VRFB with the modified GF electrode can deliver the coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of 95.0, 81.8, and 77.8 %, respectively, at 160 mA/cm2, which are much better than those of VRFB based on untreated GF.

Biomass pomelo peel modified graphite felt electrode for iron-chromium redox flow battery

Biomass pomelo peel modified graphite felt electrode for iron-chromium redox flow battery

Boosting performance of Ti3C2TX/Bi modified graphite felt electrode for all-vanadium redox flow battery

All-vanadium redox flow battery (VRFB) with high power density is urgent in energy storage area. This study investigated the impact of Ti3C2TX/Bi as catalyst on VRFB performance at high current density. The Ti3C2TX/Bi decorated electrode was prepared based on a facile dropping method. Owing to the synergistic effect between Bi and Ti3C2TX, the hydrogen evolution reaction (HER) is effectively inhibited and the electrochemical activity towards V2+/V3+ redox reaction is enhanced. With the current densities ranging from 100 mA·cm−2 to 220 mA·cm−2, VRFB equipped with Ti3C2TX/Bi modified graphite felt shows the best rate performance. Furthermore, at a current density of 200 mA·cm−2, the battery with Bi and Ti3C2TX modified electrode shows the highest capacity retention rate of 70.3 % after 100 charge-discharge cycles and the highest energy efficiency (EE) of 80.1 %.

Two birds, one stone: Deep eutectic solvent (DES) modified graphite felt electrode significantly improves performance of DES-electrolyte non-aqueous flow battery

In the past, non-aqueous redox flow batteries usually used organic solvents or ionic liquids as electrolytes. However, these two liquids are not suitable as electrolytes in terms of safety and production costs. Herein, we chose a deep eutectic solvent (DES) for non-aqueous redox flow battery. DES has been applied to play two functions in Fe/V non-aqueous redox flow battery: commercial graphite felt electrode is treated with DES and heat treatment for surface modification; DES also acts as a main electrolyte for the non-aqueous redox flow battery. While ensuring no external substances are introduced to produce side reactions, the electrode reaction kinetics are enhanced, and better cyclability is achieved. The modified treatment increases the number of oxygen-containing groups and defect sites on electrode surface. Electrode exhibits higher electrochemical activity and lower charge transfer resistance. In the full battery test, the maximum power density with modified electrode reaches 13.26 mW·cm−2, which is 114% higher than commercial graphite felt electrode. The energy efficiency reaches 90.50% and battery life is extended by 70.58% compared with commercial graphite felt electrode. This study has successfully improved the electrochemical performance of Fe/V DES redox flow battery and provides a novel idea for electrode modification.

LTO/TiO2 Nanowire-Decorated on Graphite Felt As Electrode for High-Performance Vanadium Redox Flow Battery

Vanadium redox flow battery(VRFB) is one of the most promising large-scale energy storage systems. However, the graphite electrode materials employed for VRFB often have shortcomings such as poor electrochemical activity and insufficient conductivity, which will lead to poor performance of VRFB. To modify the graphite electrode, in this study, lithium titanate/titanium dioxide(LTO/TiO2) composite catalyst with the nanowire morphology was directly grown on the surface of the heat treatment graphite felt(HGF). The graphite felt electrode through the nanowire morphology, the reaction area between the electrode and the electrolyte and active sites are increased, thereby improving the performance of VRFB. In order to further prove the effect of lithium titanate/titanium dioxide composite catalyst modified graphite felt(LTO/TiO2@HGF), the modified graphite felt electrode was applied to the positive and negative electrodes of VRFB, and the charge and discharge tests at different current densities were carried out. In terms of efficiency, the LTO/TiO2-modified graphite felt electrode has obviously better results. When the current density is increased to 200 mA/cm2, its energy efficiency can reach 60.57%, which is 8.63% higher than that of HGF. In the stability test with a current density of 160 mA/cm2, the VRFB was charged and discharged for 60 cycles, and the overall performance did not change significantly, which means that the composite material of lithium titanate and titanium dioxide not only effectively improve the performance of the VRFB, but also show the stability that can be used for a long time.

Cu supported on the graphene oxide modified graphite felt electrode for highly efficient nitrate electroreduction

To improve the stability of electrode, a Cu supported on the graphene oxide (GO) modified graphite felt (GF) electrode (Cu/GO/GF) was prepared by a simple electrodeposition method for the electrochemical reduction of nitrate in aqueous solution. The morphology, structure, and characteristics of the electrode were characterized and Cu/GO/GF was used as the cathode in an undivided cell to remove nitrate from water by electrochemical reduction. The successful electrochemical deposition of GO on GF plate and subsequent Cu coating on GO/GF electrode were observed. In presence of GO middle layer, the smaller and denser Cu distributed uniformly on the GF plate, and the electrocatalytic activity and chemical stability were remarkably improved. Cu/GO/GF electrode exhibits a higher nitrate removal efficiency of 92.5% after 100 min than Cu/GF (40.4%), GO/GF (31.6%) and GF (26.0%). The presence of Cl- (NaCl, CaCl2) and humic acid have little effect on the removal of nitrate, and Cu/GO/GF can be used for the removal of nitrate from water and wastewater.

Preparation and Properties of Indium Ion Modified Graphite Felt Composite Electrode

Iron-chromium redox flow batteries (ICRFBs) have the advantages of high safety, long cycle life, flexible design, and low maintenance costs. Polyacrylonitrile-based graphite felt composite material has good temperature resistance, corrosion resistance, large surface area and excellent electrical conductivity, and is often used as the electrode material of ICRFB, but its chemical activity is poor. In order to improve the activity of the graphite felt electrode, In3+ was used for modification in this paper, and the modified graphite felt was used as the electrode material for iron-chromium batteries. The structure and surface morphology of the modified graphite felt were analyzed by the specific surface area analyzer and scanning electron microscope; the electrochemical impedance spectroscopy and cyclic voltammetry experiments were carried out on the electrochemical workstation to study the electro catalytic activity of In3+ modified graphite felt and its performance in ICRFBS. The results show that the graphite felt electrode modified with a concentration of 0.2 M In3+ was activated at 400°C for 2 h, and its surface showed a lot of grooves, and the specific surface area reached 3.889 m2/g, while the specific surface area of the untreated graphite felt was only 0.995 m2/g significantly improved. Electrochemical tests show that the electrochemical properties of graphite felt electrodes are improved after In3+ modification. Therefore, the In3+ modified graphite felt electrode can improve the performance of ICRFB battery, and also make it possible to realize the engineering application of ICRFB battery.

Cu/Fe oxide integrated on graphite felt for degradation of sulfamethoxazole in the heterogeneous electro-Fenton process under near-neutral conditions

In the heterogeneous electro-Fenton (EF) system, high-efficiency and durable materials have attracted widespread attention as cathodes for degradation of refractory organic pollutants. In this study, a stable Cu/Fe oxide modified graphite felt electrode (Cu0.33Fe0.67NBDC-300/GF) was fabricated via a one-step hydrothermal method and subsequent thermal treatment, which used a bimetallic metal–organic framework (MOF) with 2-aminoterephthalic acid (NH2BDC) ligand as the precursor. The Cu0.33Fe0.67NBDC-300/GF electrode was used as the cathode for sulfamethoxazole (SMX) degradation in the heterogeneous EF process. The coexistence of the FeII/FeIII and CuI/CuII redox couples significantly accelerates the regeneration of FeII and promotes the generation of active free radicals (•OH and •O2−). FeIV was detected during the process, which indicates that the high-valent iron-oxo species was produced in near-neutral pH conditions. The removal efficiency of SMX (10 mg L−1) can reach 100.0% within 75 min over a wide pH range (4.0–9.0). After five cycles, the electrode retained a high stability and an outstanding catalytic capacity. Furthermore, the mechanisms and pathways for SMX degradation were proposed, the products and intermediates of SMX were analyzed, and the toxicity was evaluated. It was found that the toxicity decreased after degradation. This study displays a novel strategy for building an efficient and stable self-supporting electrode for treating antibiotic wastewater.

Electrode Materials for Enhancing the Performance of a Zinc Iodide Flow Battery at High Current Density

The zinc-iodide flow battery (ZIFB) has a high energy density and uses a benign electrolyte material [1]. However, the energy density and cyclability the ZIFB is hindered by zinc dendrite growth and electrode polarization in this battery [2]. In our previous work a new flow field design was used to mitigate dendrite formation and enhance the performance of the ZIFB [3]. Despite the enhancement achieved, capacity fade and limited cyclability at current densities greater than 20 mA cm- 2 remain a challenge for ZIFBs. In this study, the use of a high electrical conductivity material for the negative (zinc) electrode, combined with an electrocatalyst on the positive (iodide) electrode was investigated, in order to improve the cyclability and energy density of the ZIFB at high current densities.The use of a high electrical conductivity electrode has been shown to enable rapid transfer of surface charge, and maintain a uniform interfacial electric field [4]. A uniform interfacial electric field can reduce surface charge accumulation and enable a more uniform zinc deposition [5]. This leads to uniform zinc deposition and high rechargeability of the zinc electrode. In this study a copper foil was used as a high conductivity electrode material at the negative (zinc) side of the ZIFB. Scanning electron microscopy (SEM) images of the zinc deposit show that epitaxially layered deposition was obtained on the electrode surface. For all the experiments, charge/discharge of a Zn-I battery were carried out using a 3.0 M ZnI2 electrolyte on both sides of the battery, the charge and discharge current density was 40 mA cm-2, and charging was carried out to 60% state of charge. A Nafion 117 membrane was used to separate the electrolyte compartments.Nitrogen doped carbon obtained by carbonizing polyaniline (PANI) is a promising electrocatalyst material for the next generation energy storage technologies [6]. A carbonized PANI-graphite felt composite was used as the electrode material on the positive (iodide) side of the ZIFB. PANI was uniformly coated on graphite felt using brush, followed by heating to 850 °C for 2 hours under the N2 atmosphere. The use of the carbonized PANI modified graphite felt electrode material in the positive side of the ZIFB (with a graphite felt negative electrode), led to an enhancement of the energy efficiency of around 4% (from 67 % to 71%) at a current density of 40 mA cm-2. The carbonized-PANI modified electrode was characterized using X-ray diffraction, Raman spectroscopy, nitrogen adsorption, and SEM. SEM results indicated that agglomerated nano-grains of carbonized PANI were distributed on the graphite felt fibers. Nitrogen adsorption analysis confirmed that the carbonized PANI-graphite felt electrode had a higher specific surface area than the pristine graphite felt.The performance of a ZIFB using a carbonized PANI-graphite felt positive electrode, and a copper foil negative electrode was evaluated by cycling for over 100 cycles. Stable cycling was observed, with a coulombic efficiency of 99%. When compared with using pristine graphite felt on the negative and positive electrodes, a significant improvement in the charge-discharge energy efficiency of around 10 % (from 67 % to 76%) was obtained.

Performance improvement of non-aqueous iron-vanadium flow battery using chromium oxide–modified graphite felt electrode

Performance improvement of non-aqueous iron-vanadium flow battery using chromium oxide–modified graphite felt electrode

Nitrogen-doped carbon spheres-decorated graphite felt as a high-performance electrode for Fe based redox flow batteries

In this paper, the performance of Fe-based redox flow batteries (IRFBs) was dramatically improved by coating N-doped carbon spheres (NDCS) on the graphite felt electrodes. NDCS was synthesized by the single-step hydrothermal method using dextrose and ammonia as a precursor and coated over graphite felt electrodes by electrostatic spraying. The weight of NDCS required for the modification of the electrode to achieve the effective performance of the battery was studied using electrochemical techniques. Cyclic voltammetry (CV) and potentiodynamic polarization study was used to evaluate the kinetic reversibility and linear polarization resistance offered by the electrode towards electrolyte. The characterizing features of the NDCS, untreated graphite felt (UGF) electrode and optimized modified graphite felt (MGF) electrode were analyzed using SEM, EDAX, XRD, and Raman spectroscopy. The charge-discharge studies were performed for the 132 cm2 IRFB using a 2 mg/cm2 MGF electrode as a positive electrode by varying the current densities from 20 to 60 mA/cm2. The cell resulted in an average coulombic efficiency (CE) of 93%, voltaic efficiency (VE) of 72%, and energy efficiency (EE) of 68% for 15 cycles at the current density of 30 mA/cm2. The improvement in the performance of the IRFB is due to the presence of electrochemically active nitrogen-bearing carbon catalysts. In this paper, the pioneering effort has been made to improve the efficiency of the IRFB with an active area of 132 cm2 using glycine as the ligand.

Enhanced electro-Fenton catalytic performance with in-situ grown Ce/Fe@NPC-GF as self-standing cathode: Fabrication, influence factors and mechanism

Heterogeneous electro-Fenton (E-F) is considered as an attractive technique for efficient removal of refractory organic pollutants in wastewater. The regeneration of FeII and catalyst reusability are key issues for effective and sustainable degradation. Developing binder-free iron phase/carbon composite cathode is a feasible strategy. In this work, the stable Ce/Fe-nanoporous carbon modified graphite felt electrode (Ce/Fe@NPC-GF) was fabricated using in situ solvothermal method and subsequent carbonization treatment, which worked as the cathode in a heterogeneous electro-Fenton system to degrade sulfamethoxazole. The electrocatalytic activity was significantly improved with doping of Ce. It was found that mesoporous Ce/Fe@NPC-GF cathode demonstrated high oxygen reduction activity and low resistance. The co-existence of FeⅡ/FeⅢ and CeⅢ/CeⅣ redox couples enhanced remarkably interfacial electron transfer, promoting in-situ H2O2 generation and decomposition, sequentially boosting the production of reactive radicals (·OH and ·O2−). Under 20 mA and pH 3, Sulfamethoxazole (SMX) was basically degraded in 120 min, and the removal rate was satisfactory in wide pH (2–6). After 8 cycles, the electrode could still maintain high stability and outstanding catalytic capacity. This work displayed a novel in-situ preparation method of composite cathode with excellent catalytic performance in E-F system, which offered inspiration for developing efficient heterogeneous electro-Fenton cathode material.

Ultra-micro amperometric sensor of isoniazid using carbon doped vanadium trioxide @ Prussian blue supported on graphite felt

A sensitive and selective amperometric determination method for isoniazid (INZ), an anti-tuberculosis drug, was studied by cyclic voltammetry and chronoamperometry, using carbon doped vanadium trioxide @ Prussian blue modified graphite felt electrodes (V2O3-C@PB/GF). V2O3-C was synthesized by a solvothermal technique and fixed on GF; then PB was generated on the so-obtained V2O3-C/GF. The morphology and structure of the composite electrode were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and ultraviolet-visible (UV–vis) spectroscopy. After optimization of the parameters influencing the formation of V2O3-C@PB/GF, the composite electrode showed efficient electrocatalytic performance for isoniazid detection in 0.5 M potassium chloride (KCl) solution. A wide linear concentration range (2.5 ×10-9–1.1 ×10-3 M), a good sensitivity (1.378 A/M, 0.561 A/M) and a low detection limit (0.83 nM) were obtained. Furthermore, long-term stability and fabrication reproducibility of the electrochemical device have been investigated, as well as its robustness to interferent species. Finally, the practical applicability of the proposed sensor was assessed by detecting INZ in commercial tablets, bovine serum albumin and human urine samples: recovery values varied from 96.8% to 105.2%, indicating an excellent analytical performance for INZ qualification.

Simultaneous removal of pyridine and denitrification in an integrated bioelectro-photocatalytic system utilizing N-doped graphene/α-Fe2O3 modified photoanode

In order to realize simultaneous removal of pyridine and denitrification, an integrated bioelectro-photocatalytic system (IBPS) equipped with N-doped graphene/α-Fe2O3 modified graphite felt (GF) photoanode and GF biocathode was constructed and operated in ON-OFF illumination mode. Compared to α-Fe2O3 modified GF electrode, N-doped graphene/α-Fe2O3 modified photoanode showed superior stability, photo-electrochemical and catalytic activity owing to the excellent electron transporting properties of N-doped graphene and unique structure of N-doped graphene/α-Fe2O3 composite. In IBPS, ammonia produced from pyridine photocatalytic degradation diffused from anode to biocathode through the cation-exchange membrane. Simultaneous nitrification and denitrification were realized in the biocathode chamber under limited dissolved oxygen. At the same time, the harvested photo-electrons derived from photoanode were delivered to the biocathode via an external circuit for enhanced denitrification. Complete removal of pyridine and high TOC removal efficiency of 85.90 ± 5.48% in the anode and complete denitrification in the biocathode after four ON-OFF cycles (96 h) reaction were achieved. Furthermore, the underlying mechanism for the enhanced removal of pyridine and denitrification was proposed preliminarily. This integrated reactor synergically utilized photoenergy, electrical energy and bioenergy for removal of pyridine and denitrification, showing a promising future in designing new systems for water environmental remediation from solar energy.

Electrochemical performance of graphene oxide modified graphite felt as a positive electrode in all-iron redox flow batteries

In this study, we demonstrate that coating a layer of graphene oxide (GO) onto graphite felts (GF) by electrostatic spraying can substantially increase the performance of all-iron redox flow batteries (IRFBs). Graphite felts are extensively used as electrodes but they do not have the desired electrochemical properties. GO has good electrochemical features. Hence, GO was synthesized from graphite powder and applied onto graphite felts. Chemical and structural features of the bare graphite felt electrode (BGF), thermally treated graphite felt electrode (TTGF), and graphene oxide modified graphite felt electrode (GOMGF) were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Transmission Electron Microscopy (TEM), Raman Spectroscopy (RS), X-Ray Photoelectron Spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analysis. Similarly, the electrochemical performance was evaluated using Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Tafel analysis and charge–discharge experiments. The Charge–discharge experiments were performed at 1 to 5 mgcm−2 weight of GO on the modified graphite felt electrode and varying the current densities from 10 to 40 mAcm−2. The coulombic efficiency (ηC) and energy efficiency (ηE) of the cell determined at 20 mAcm−2 for 4 mgcm−2-GOMGF electrodes were found to be 64.61% and 50.27%, respectively. Among the three different types of electrodes, the GOMGF electrode showed better electrocatalytic performance mainly due to the excellent conducting network of the defective edges of oxygen on the surface of layered flakes of the GO. After twenty cycles, the average ηC and ηE of the cell using a 4 mgcm−2-GOMGF electrode were found to be 62.06% and 42.02%, respectively.

Improved performance of iron-based redox flow batteries using WO3 nanoparticles decorated graphite felt electrode

Iron flow batteries are having tremendous attraction because of their economic feasibility and environmentally favorable electrolytes. Electrode and electrolyte used in iron-based redox flow batteries (IRFBs) have a vital role in the performances of electrochemical energy storage devices. Therefore designing a suitable electrode and optimization of electrolyte composition is highly needed. Graphite is one of the appropriate electrodes used in flow batteries but they have to be modified to improve the electrical performance. Here, for the first time, WO3 nanoparticles (WONs) were used to modify graphite felt electrode for IRFBs applications. The effect of loading mass per unit cm2 of electrochemically active material has been investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (Tafel) studies. The ligand based iron-electrolyte along with anion exchange membrane has been selected for the studies. The performance of the modified graphite felt electrode (3 mg/cm2) assembled in 132 cm2 cell results in a peak power density of 53 mW/cm2 at 40 mA/cm2. This study provides information about the improvement in the electrochemical performance of IRFBs.