Hydrogen‐Treated Rutile TiO<sub>2</sub> Shell in Graphite‐Core Structure as a Negative Electrode for High‐Performance Vanadium Redox Flow Batteries

Vázquez‐Galván, Javier; Flox, Cristina; Fàbrega, Cristian; Ventosa, Edgar; Parra, Andrés; Andreu, Teresa; Morante, Joan Ramón

doi:10.1002/cssc.201700017

Cited by 63 publications

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“…For example, MWCNTs [5], graphene nanosheets and carbon nanofibers [6,7], functionalization of carbon surface as N-and Ocontaining groups [8], metals such as Pt [6], Ir [9] and Bi [10] and metal oxides Mn 3 O 4 [11,12], WO 3 [13,14], TiO 2 [15], CeO 2 [16], PbO 2 [17], and Nb 2 O 5 [18] were deposited onto the CF supports to prepare modified electrodes. However, although all this research demonstrated an improvement in electrochemical kinetics, the enhanced power density is rarely discussed in the literature as a complementary performance evaluation to the charge/discharge experiments.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

Hosseini

Mousavihashemi

Murcia-López

et al. 2018

Carbon

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Although Vanadium Redox Flow Battery (VRFB) is well suitable for grid-scale application, their power-related cost must be reduced in order to boost the technology to the market, allowing their widespread commercialization. One effective way to make the VRFB a competitive and viable solution could be through the new strategies for improving the electrocatalytic activity of the electrodes with enhanced electrolyte/electrode interface characteristics. The greatly effective and enhanced-electron transfer could increase the current density with the decrement of the stack size. Herein, we report the synergistic effect demonstrated by N-and WO 3 -decorated carbon-based positive electrode, named HTNW electrode, which demonstrates the feasibility of achieving: i) enhanced electrocatalytic activity, indicating high rate towards VO 2+ /VO 2 + couple (promotion of oxygen and electron transfer processes), ii) decrement of the electron-transfer resistance from 75.62 Ω to 12.4 Ω for the pristine electrode and HTNW electrodes, respectively; iii) 51% of the electrolyte utilization ratio at high rates (i.e. 200 mA cm -2 ) with 70% of energy efficiency ; iv) increment of more than 50% of the power-peak in comparison with HT electrode.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

Hosseini

Mousavihashemi

Murcia-López

et al. 2018

Carbon

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“…It is also clear that the TiO 2 passivation layer can also play a role on the HER. It has been demonstrated that it can effectively hinder this reaction thanks to the strong proton adsorption on the TiO 2 , which might restrict H 2 formation . However, besides having an effect in this aspect, TiO 2 layers have been used as protective layers of silicon photovoltaics, thanks to its good stability at different pH conditions, especially when it is not polarized at very negative potentials .…”

Section: Figurementioning

confidence: 99%

“…[9] One important aspectt oc onsider in the design of this kind of SPEES is the overall cell voltage required to be supplied by the semiconductor.I nterestingly,t he photocharge process in VRFBsh as only been applied to thea nodic reaction (VO 2 + /VO 2 + ), even in full-cell configuration. Although both halfreactionsh ave inherent limitations and the kinetics associated to each one strongly depends on the features of the used electrode,t he negative reaction (V 3 + /V 2 + )c an be ad etermining step because of parasitic reactions such as the hydrogen evolution reaction( HER), [10] which is kinetically more favored and might cause imbalances and decrease in performance, and because of easy reoxidationo fV 2 + under normal operating conditions. Regarding this aspect, it is possible to improve the overall performance of SPEES systems by following the strategies developed in VRFBs, which is where electrochemical studies relatedt ot he interface control are essential.…”

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confidence: 99%

“…It has been demonstrated that it can effectively hinder this reactiont hanks to the strong protona dsorption on the TiO 2 ,w hich might restrict H 2 formation. [10] However,b esides having an effect in this aspect, TiO 2 layers have been used as protective layers of silicon photovoltaics, thanks to its good stability at different pH conditions, especially when it is not polarized at very negative potentials. [14] Interestingly,t he obtainedr esults with the photocathode in presence of bismuth evidence that less negative voltages are necessary for performing the electrochemical reaction, so that lessh arsh conditions are necessary during cycling, assuring better stability for the photoelectrode and the TiO 2 protectivel ayer.After these tests, measurements with the photocathodes were performed under chopped illumination ( Figure S2).…”

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Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

et al. 2017

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The ability of crystalline silicon to photoassist the V 3 + /V 2 + cathodic reaction under simulated solar irradiation, combined with the effect of bismuth have led to important electrochemical improvements. Besides the photovoltage suppliedb yt he photovoltaics, additional decrease in the onset potentials, high reversibility of the V 3 + /V 2 + redox pair,a nd improvement in the electrokinetics were attained thanks to the addition of bismuth. In fact, Bi 0 deposition has shown to slightly decrease the photocurrent, but the significant enhancement in the charge transfer,r eflected in the overall electrochemical performance clearly justifiesi ts use as additive in ap hotoassisted system for maximizing the efficiency of solar charge to battery.The electrical conversion and storage of solar energy is ac rucial target for assuringt he world energy supply in the long term. Because of the current maturity of the photovoltaic( PV) technology,s ystems devoted to PV electricity or to photoelectrochemical (PEC) approaches for water splitting have been strongly developed in the last years. [1,2] However,b ecause of the sluggish kineticsa ssociated to the water oxidationr eaction [3] and of inherent limitations in the H 2 economy,t he possibility of storing energy by coupling PV systems to other kind of redox pairs has recently attracted more attention, giving rise to the so-calleds olar-powered electrochemical energy storage (SPEES), [4] in which two systems, aP Va nd ab attery,a re integrated in as ingle device with potential advantages such as chargingb yusing solar light.Among other technologies, the vanadium redox flow batteries (VRFBs) are ar obust alternative to be integrated into SPEES with several advantages:d ecoupling of energy and power, use of the same elementi nb oth half-reactions and possibility of large-scale development. Previously,s ome studies reported the combination of PEC systems in VRFBs, such as TiO 2 [5] and TiO 2 / WO 3 photoanodes, [6] and CdS thin films in tandem with dyesensitized solar cells. [7] Particularly in the second case, an unbiaseds ystem reaching ap romising state of charge was achieved,a lthought he long-term stability in acid electrolyte and the low chargec urrent attained by the semitransparent CdS film were substantial limitations. These systems also have significant restraints associated to the low photon absorption in comparison to other absorbers. Crystalline silicon has also been integrated as light absorber in aq uinone/bromine biasfree redox flow battery. [8] For that purpose,surface-buried junctions were used as photoelectrodes in both half-reactionsa ttainingt he necessary charge voltage upon illumination (photovoltage % 1V)i nasystem involvingaPEC cell and aR FB. Despite the promising results, it should be pointed out that the associated cell voltage for theseo rganic redox couples can only attain am aximum cell voltage of % 0.89 V, which is lower than that of VRFBs. [9] One important aspectt oc onsider in the design of this kind of SPEES is the overall cell voltage re...

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“…The other method is heterocarbon doping with elements such as N, P, O, F, Cl, and Br. [19][20][21][22][23][24][25][26][27][28][29][30] The introduction of these heterocarbon impurities not only provides catalytic sites but also reduces the degree of graphitization and improves the degree of defects on the carbon fiber surface. Therefore, such modification improves the catalytic performance of electrode materials.…”

Section: Introductionmentioning

confidence: 99%

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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Hydrogen‐Treated Rutile TiO₂ Shell in Graphite‐Core Structure as a Negative Electrode for High‐Performance Vanadium Redox Flow Batteries

Cited by 63 publications

References 47 publications

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

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

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Hydrogen‐Treated Rutile TiO2 Shell in Graphite‐Core Structure as a Negative Electrode for High‐Performance Vanadium Redox Flow Batteries

Cited by 63 publications

References 47 publications

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

High-power positive electrode based on synergistic effect of N- and WO3 -decorated carbon felt for vanadium redox flow batteries

Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

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

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Hydrogen‐Treated Rutile TiO₂ Shell in Graphite‐Core Structure as a Negative Electrode for High‐Performance Vanadium Redox Flow Batteries