High efficiency of CO 2 -activated graphite felt as electrode for vanadium redox flow battery application

Chang, Yu-Chung; Chen, Jianyu; Kabtamu, Daniel Manaye; Lin, Guan-Yi; Hsu, Ning-Yih; Chou, Yi-Sin; Wei, Hung-Ju; Wang, Chenhao

doi:10.1016/j.jpowsour.2017.07.103

Cited by 98 publications

(49 citation statements)

References 49 publications

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“…The source of the oxygen in the newly created functional groups evidence with XPS was not specified. Short treatment of graphite felt in an atmosphere of CO 2 resulted in a highly active material [347]. Improvements even better than after treatment in nitrogen atmosphere, as evidenced by increased peak currents in CVs and decreased charge transfer resistance in impedance measurements, were attributed to enlarged surface area (10 fold BET), enhanced wettability, and increased number of oxygen-containing functional groups.…”

Section: Mechanical Thermal or Chemical Surface Treatmentmentioning

confidence: 99%

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Holze

2018

Batteries

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Flow batteries (also: redox batteries or redox flow batteries RFB) are briefly introduced as systems for conversion and storage of electrical energy into chemical energy and back. Their place in the wide range of systems and processes for energy conversion and storage is outlined. Acceleration of electrochemical charge transfer for vanadium-based redox systems desired for improved performance efficiency of these systems is reviewed in detail; relevant data pertaining to other redox systems are added when possibly meriting attention. An attempt is made to separate effects simply caused by enlarged electrochemically active surface area and true (specific) electrocatalytic activity. Because this requires proper definition of the experimental setup and careful examination of experimental results, electrochemical methods employed in the reviewed studies are described first.

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Section: Mechanical Thermal or Chemical Surface Treatmentmentioning

confidence: 99%

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Holze

2018

Batteries

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“…The kinetics of the positive half‐cell reaction is slow compared to the negative half‐cell, so the rate limitation is coming from the former [7,8] . Chemical, thermal, and electrochemical oxidative treatment is widely investigated to improve the graphite felts’ electroactivity [9–11] . These oxidative approaches fabricate different oxygenic groups (epoxy, OH, COOH, C=O) on the electrodes and increase the sp 3 hybridization of the carbon atoms in the material.…”

Section: Introductionmentioning

confidence: 99%

The Role of Oxygenic Groups and sp³ Carbon Hybridization in Activated Graphite Electrodes for Vanadium Redox Flow Batteries

et al. 2021

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Graphite felt is a widely used electrode material for vanadium redox flow batteries. Electrode activation leads to the functionalization of the graphite surface with epoxy, OH, C=O, and COOH oxygenic groups and changes the carbon surface morphology and electronic structure, thereby improving the electrode's electroactivity relative to the untreated graphite. In this study, density functional theory (DFT) calculations are conducted to evaluate functionalization's contribution towards the positive half‐cell reaction of the vanadium redox flow battery. The DFT calculations show that oxygenic groups improve the graphite felt's affinity towards the VO2+/VO2+ redox couple in the following order: C=O>COOH>OH> basal plane. Projected density‐of‐states (PDOS) calculations show that these groups increase the electrode's sp3 hybridization in the same order, indicating that the increase in sp3 hybridization is responsible for the improved electroactivity, whereas the oxygenic groups’ presence is responsible for this sp3 increment. These insights can aid the selection of activation processes and optimization of their parameters.

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“…We can conclude that coating and modification caused great changes in the electrode surface morphology because the intensity ratio of the I D / I G band increased from 0.897 for GF to 1.01 for 2‐0/GF, 1.02 for 0‐2/GF, and 1.06 for 2‐2/GF, which indicated a reduction in the degree of graphitization and an increase in the number of defects. These phenomena indicate an increase in the number of catalytic sites …”

Section: Resultsmentioning

confidence: 95%

Surface‐Wrinkle‐Modified Graphite Felt with High Effectiveness for Vanadium Redox Flow Batteries

Chen

Gao

Zhang

et al. 2019

Adv Elect Materials

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obstacles, such as energy instability and difficulties connecting to the high-voltage line transmission network. An effective solution is to develop low-cost and highefficiency large-scale energy storage equipment to use with such energy sources. [1][2][3][4][5] In electrochemical energy storage technologies, such as Li-ion batteries, Pb-acid batteries, and flow batteries, flow batteries, especially vanadium redox flow batteries (VRFBs), have attracted interest due to their flexible energy and power density design, low cost, lack of cross contamination, and long cycle life. Unlike other liquid-flow batteries, the phenomenon of positive and negative electrode liquid cross contamination does not occur in the recycling process of VRFBs because the positive and negative electrolytes are both based on vanadium ions. [3,[6][7][8][9][10] VRFBs mainly consist of battery stacks and positive and negative electrolyte tanks. The positive/negative electrolyte is pumped into the stack and reacts at the electrodes (Equations (1) and (2)). A Nafion-series membrane separates the cathode and anode and has a strong influence on the coulombic efficiency and energy efficiency (EE) of the battery. Therefore, an excellent vanadium battery membrane should not only ensure the passage of hydrogen ions but also limit the transmission of vanadium ions. [11][12][13][14][15] When the electronic gains and losses of VO 2+ /VO 2 + and V 2+ /V 3+ couples occur, the electrodes play an important catalytic role and provide a site for chemical reactions. Therefore, the catalytic activity of the electrode is very important for the capacity and efficiency of VRFBs VO H O VO 2H e 1.00 V vs NHE 2 2 2 E o + + + = + + + −There are two main materials that can be used as VRFB electrodes, metals and carbon-based materials. Metal electrodes are mainly precious metals, which have high catalytic activity, but their high cost and poor stability limit their commercial application. In practical applications, carbon-based materials, such as carbon cloth and graphite felt (GF), which are based on good mechanical strength and electrolyte resistance, are commercially available. However, the smooth and uniform surfaces of carbon-based materials lack sufficient catalytic sites, resulting in poor catalytic activity and limiting the further improvement of battery performance. [2,[16][17][18] Many researchers have tried Surface-wrinkle-modified graphite felt (GF) with abundant N and O is prefabricated by a hydrothermal method followed by calcination, and its surface morphology, elemental composition, and electrochemical properties are characterized by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and charge/discharge tests. The highly folded coating has excellent wettability, abundant catalytic sites, a fast ion-diffusion rate, ultralow interface transfer resistance, and high catalytic activity for VO 2+ /VO 2 + and V 2+ /V 3+ reaction couples. Compared with the original GF, t...

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High efficiency of CO 2 -activated graphite felt as electrode for vanadium redox flow battery application

Cited by 98 publications

References 49 publications

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

The Role of Oxygenic Groups and sp³ Carbon Hybridization in Activated Graphite Electrodes for Vanadium Redox Flow Batteries

Surface‐Wrinkle‐Modified Graphite Felt with High Effectiveness for Vanadium Redox Flow Batteries

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High efficiency of CO 2 -activated graphite felt as electrode for vanadium redox flow battery application

Cited by 98 publications

References 49 publications

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

The Role of Oxygenic Groups and sp3 Carbon Hybridization in Activated Graphite Electrodes for Vanadium Redox Flow Batteries

Surface‐Wrinkle‐Modified Graphite Felt with High Effectiveness for Vanadium Redox Flow Batteries

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The Role of Oxygenic Groups and sp³ Carbon Hybridization in Activated Graphite Electrodes for Vanadium Redox Flow Batteries