Optimization of thermal oxidation of electrodes for the performance enhancement in all-vanadium redox flow betteries

Ghimire, Purna C.; Schweiss, Ruediger; Scherer, Günther G.; Lim, Tuti Mariana; Wai, Nyunt; Bhattarai, Arjun; Yan, Qingyu

doi:10.1016/j.carbon.2019.08.068

Cited by 50 publications

(39 citation statements)

References 61 publications

(70 reference statements)

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“…These have attempted to alter the surface activation, pore size distribution and functionalisation with an extensive array of species [19,20,49]. In almost all cases, surface pre-treatment is critical and these include: chemical oxidation [50], oxygen plasma [14], gamma irradiation [14], spark discharge [51], thermal air oxidation [14,52,53], laser ablation [54] and various electrochemical techniques [55][56][57]. A brief summary of the more recent approaches are highlighted in Table 1.…”

Section: Alternative Pre-treatment Processesmentioning

confidence: 99%

Ultrasonic exfoliation of carbon fiber: electroanalytical perspectives

et al. 2020

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Electrochemical anodisation techniques are regularly used to modify carbon fiber surfaces as a means of improving electrochemical performance. A detailed study of the effects of oxidation (+ 2 V) in alkaline media has been conducted and Raman, XPS and SEM analyses of the modification process have been tallied with the resulting electrochemical properties. The co-application of ultrasound during the oxidative process has also been investigated to determine if the cavitational and mass transport features influence both the physical and chemical nature of the resulting fibers. Marked discrepancies between anodisation with and without ultrasound is evident in the C1s spectra with variations in the relative proportions of the electrogenerated carbon-oxygen functionalities. Mechanisms that could account for the variation in surface species are considered. Graphic abstract

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Section: Alternative Pre-treatment Processesmentioning

confidence: 99%

Ultrasonic exfoliation of carbon fiber: electroanalytical perspectives

et al. 2020

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“…However, T‐CF with the least graphitization degree possesses the highest charge transfer resistance to the positive reaction. Thus, benefits with respect to electrochemical activity for Fe 2+ /Fe 3+ couple could not only be attributed to the oxygen functional groups …”

Section: Resultsmentioning

confidence: 99%

“…Thus, benefits with respect to electrochemical activity for Fe 2+ /Fe 3+ couple could not only be attributed to the oxygen functional groups. 48 In the negative reaction of Cr 3+ /Cr 2+ couple, the relationship of R ct values is R ct (T -CF) > R ct (T -GF) > R ct (CF) > R ct (GF). Although the reaction peak current of T-GF and T-CF is enhanced as a result of the oxygen functional groups and the specific surface area, the charge transfer resistance of negative reaction on the surface of GF and CF becomes smaller, which is likely to be related to the deposition of the catalyst.…”

Section: And Eis Analysismentioning

confidence: 99%

Investigations on physicochemical properties and electrochemical performance of graphite felt and carbon felt for iron‐chromium redox flow battery

et al. 2020

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Summary In this paper, polyacrylonitrile‐based graphite felt (GF), carbon felt (CF) and the effect of thermal activation on them with or without the catalyst (BiCl3) are comprehensively investigated for iron‐chromium redox flow battery (ICRFB) application. The physical‐chemical parameters of GF and CF after the thermal activation is affected significantly by their graphitization degree, oxygen functional groups, and surface area. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results manifest that GF and CF before and after the thermal activation have different electrocatalytic activities owing to oxygen functional groups number increase and the graphitization degree decrease. In terms of the capacity decay rate, as oxygen functional groups provide shorter electrocatalytic pathways than bismuth ions, the performance of GF and CF after the thermal activation is more ideal. As a result, GF before and after the thermal activation exhibits higher efficiency (EE: 86%) and better stability at a charge‐discharge current density of 60 mA·cm−2 than those of CF during charge‐discharge cycling, as the dominant limitation in an ICRFB is ohmic and activation polarization. Therefore, GF after thermal activation together with the addition of BiCl3 in the electrolyte is a more promising electrode material for ICRFBs application than CF.

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“…Various modification techniques are implemented to activate the carbon felt to enhance the overall performance of the cell. Modification techniques include thermal [17][18][19][20][21][22], chemical [23][24][25], plasma etching [19], corona discharge [26], impregnation of catalyst [27][28][29][30][31][32][33][34][35], etc. Ion exchange membranes separate the two half-cells, and allow transport of the charge balancing ions, such as H + , SO 4 2− and HSO 4 − [36].…”

Section: Introductionmentioning

confidence: 99%

In-Situ Tools Used in Vanadium Redox Flow Battery Research—Review

Ghimire¹,

Bhattarai²,

Lim

et al. 2021

Batteries

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Progress in renewable energy production has directed interest in advanced developments of energy storage systems. The all-vanadium redox flow battery (VRFB) is one of the attractive technologies for large scale energy storage due to its design versatility and scalability, longevity, good round-trip efficiencies, stable capacity and safety. Despite these advantages, the deployment of the vanadium battery has been limited due to vanadium and cell material costs, as well as supply issues. Improving stack power density can lower the cost per kW power output and therefore, intensive research and development is currently ongoing to improve cell performance by increasing electrode activity, reducing cell resistance, improving membrane selectivity and ionic conductivity, etc. In order to evaluate the cell performance arising from this intensive R&D, numerous physical, electrochemical and chemical techniques are employed, which are mostly carried out ex situ, particularly on cell characterizations. However, this approach is unable to provide in-depth insights into the changes within the cell during operation. Therefore, in situ diagnostic tools have been developed to acquire information relating to the design, operating parameters and cell materials during VRFB operation. This paper reviews in situ diagnostic tools used to realize an in-depth insight into the VRFBs. A systematic review of the previous research in the field is presented with the advantages and limitations of each technique being discussed, along with the recommendations to guide researchers to identify the most appropriate technique for specific investigations.

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Optimization of thermal oxidation of electrodes for the performance enhancement in all-vanadium redox flow betteries

Cited by 50 publications

References 61 publications

Ultrasonic exfoliation of carbon fiber: electroanalytical perspectives

Ultrasonic exfoliation of carbon fiber: electroanalytical perspectives

Investigations on physicochemical properties and electrochemical performance of graphite felt and carbon felt for iron‐chromium redox flow battery

In-Situ Tools Used in Vanadium Redox Flow Battery Research—Review

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