Enhanced performance of a Bi-modified graphite felt as the positive electrode of a vanadium redox flow battery

González, Zoraida; Sanchez, Adrian J.; Blanco, Clara; Granda, Marcos; Menéndez, Rosa; Santamarı́a, Ricardo

doi:10.1016/j.elecom.2011.08.017

Cited by 176 publications

(98 citation statements)

References 17 publications

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“…It suggests that Cr 3+ with high concentration increases the reaction capability of V(V)/V(IV) couple. Correspondently, the electrode activity is improved [10,11].…”

Section: Discussionmentioning

confidence: 99%

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Influence of Cr3+ concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries

et al. 2012

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The composition of electrolyte affects to a great extent the electrochemical performance of vanadium redox flow batteries (VRB). The effects of Cr 3+ concentration in the anolyte on the electrode process of V(V)/V(IV) couple have been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was found that Cr 3+ causes no side reactions, but affects the electrochemical performance of V(V)/V(IV) redox reaction, including the reaction activity, the reversibility of electrode reaction, the diffusivity of vanadium ions, the interface film impedance, and the electrode reaction impedance. The experimental results show that Cr 3+ within a certain concentration range can improve the reversibility of electrode reaction and the diffusion of vanadium ions. With the Cr 3+ concentration increasing from 0 to 0.30 g L −1, the reversibility of V(V)/V(IV) reaction increases, while the diffusion resistance decreases. Correspondingly, the diffusion coefficient of vanadium ions increases from (5.48-6.77) × 10 −7 to (6.82-8.44) × 10 −7 cm 2 s −1 , an increase of ~24%. However, the diffusion resistance increases and the diffusion coefficient decreases when Cr 3+ concentration is over 0.30 g L −1 , while the impedances of the interface, the film as well as the charge transfer increase continuously. As a result, Cr 3+ with a certain concentration improves the diffusion and mass transfer process, but the resistances of the film, the interface, and the charge transfer rise. Furthermore, Cr 3+ concentration of no more than 0.10 g L −1 has few effect on the electrode reaction process, and that of no more than 0.30 g L −1 is favorable to the diffusion of vanadium ions. Vanadium redox flow batteries (VRB), a high efficient and clean rechargeable device for energy conversion and storage, have promising prospects in the fields of generating electricity using renewable power sources, peak regulation of electric networks, emergency power, remote supply and electric vehicles. They have unique advantages such as high power density, excellent cycling stability, high reliability, simple operation and convenient maintenance [1]. The process of energy storage and release of VRB is generally achieved through an interconversion of soluble redox couples like V(V)/V(IV) and V(III)/V(II) in a electrolyte. Thus, the electrolyte is both the electroactive species and the reservoirs for energy storage, and has a determining influence on the electrochemical performance of VRB. The anolyte can be prepared directly by dissolving VOSO 4 in a dilute sulfuric acid solution [2]. However, it is usually prepared by dissolving V 2 O 5 in a dilute sulfuric acid with a reduction treatment because of the high cost of VOSO 4 [3]. V 2 O 5 is an intermediate product in the smelting process for producing steel in Pangang Group, but it usually contains small amounts of impurities, such as Cr 3+ , Mn 2+ ions, which exist also in the VOSO 4 prepared by using such V 2 O 5 . We have investigated the influence of Mn 2+ concentration on the electroc...

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“…It suggests that Cr 3+ with high concentration increases the reaction capability of V(V)/V(IV) couple. Correspondently, the electrode activity is improved [10,11].…”

Section: Discussionmentioning

confidence: 99%

“…It indicates that Cr 3+ with a certain concentration reduces the electrode polarization, and improves the reaction activity [10][11][12]. On the other hand, the increase of Cr 3+ concentration results in the ratio of I pO /I pR near to 1.…”

Section: Discussionmentioning

confidence: 99%

Influence of Cr3+ concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries

et al. 2012

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“…There are several popular strategies reported in the literature including oxidation of the active material, and/or the addition of electrocatalytic nanoparticles for more facile kinetics. 38,39 Nevertheless, the presence of pronounced redox peaks demonstrates the utility of MWCNTs as the conductive material for redox electrolytes.…”

Section: Methodsmentioning

confidence: 99%

Flowable Conducting Particle Networks in Redox-Active Electrolytes for Grid Energy Storage

Hatzell

Boota

Kumbur

et al. 2015

J. Electrochem. Soc.

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This study reports a new hybrid approach toward achieving high volumetric energy and power densities in an electrochemical flow capacitor for grid energy storage. The electrochemical flow capacitor suffers from high self-discharge and low energy density because charge storage is limited to the available surface area (electric double layer charge storage). Here, we examine two carbon materials as conducting particles in a flow battery electrolyte containing the VO 2+ /VO 2 + redox couple. Highly porous activated carbon spheres (CSs) and multi-walled carbon nanotubes (MWCNTs) are investigated as conducting particle networks that facilitate both faradaic and electric double layer charge storage. Charge storage contributions (electric double layer and faradaic) are distinguished for flow-electrodes composed of MWCNTs and activated CSs. A MWCNT flow-electrode based in a redox-active electrolyte containing the VO 2+ /VO 2 + redox couple demonstrates 18% less self-discharge, 10 X more energy density, and 20 X greater power densities (at 20 mV s −1 ) than one based on a non-redox active electrolyte. Furthermore, a MWCNT redox-active flow electrode demonstrates 80% capacitance retention, and >95% coulombic efficiency over 100 cycles, indicating the feasibility of utilizing conducting networks with redox chemistries for grid energy storage. Grid energy storage is a critical component toward the integration of renewable energy technologies and ensuring reliable distribution of electricity.1,2 Numerous flow-assisted electrochemical systems (FAESs) based on different active materials are being pursued including redox flow batteries (RFB), 3-5 semi-solid flow batteries, 6,7 organic-redox flow batteries, [8][9][10] and the electrochemical flow capacitor (EFC).11,12 A flow-architecture provides for scalable and modular systems, decoupled power and energy densities, and a potentially low-cost means for storing energy at the grid level (Fig. 1a).All FAESs utilize active materials either dissolved in an electrolyte solution or suspended in an electrically conductive flow-electrode for scalable energy storage (Fig. 1). Redox-flow batteries and organicredox flow batteries both utilize soluble redox species as the active materials (Figs. 1c and 1d). In traditional RFBs, soluble metal ions (vanadium, cerium, iron, etc.) are used, while organic RFBs utilize soluble organic compounds (e.g. quinones) as active material. Metal ions have been widely studied in commercial RFBs and are the closest technology to be widely used. FAESSs based on organic compounds are new and promising for grid energy storage applications because they do not rely on precious metals, have tunable properties based on their chemical structure, 13,14 and have the potential to be low-cost, durable, environmentally friendly, and scalable. Both of these systems rely on chemical reactions based on heterogeneous charge transfer for charge storage. Vanadium compounds have been known to have sluggish kinetics when compared to quinone-based molecules, which undergo rapid t...

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“…On the other hand, modified graphite felts have been widely used as electrodes in redox flow batteries and have demonstrated their ability to withstand oxidant environments while maintaining a good electrical conductivity and performing well as an "electron-transfer surface" [33][34][35].…”

Section: Selection Of Electrode Materialsmentioning

confidence: 99%

Enhanced energy density of carbon-based supercapacitors using Cerium (III) sulphate as inorganic redox electrolyte

Díaz

González

Santamarı́a

et al. 2015

Electrochimica Acta

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The energy density of carbon based supercapacitors (CBSCs) was significantly increased by the addition of an inorganic redox species [Ce 2 (SO 4 ) 3 ] to an aqueous electrolyte (H 2 SO 4 ). The development of the faradaic processes on the positive electrode not only significantly increased the capacitance but also the operational cell voltage of these devices (up to 1.5 V) due to the high redox potentials at which the Ce 3+ /Ce 4+ reactions occur. Therefore, in asymmetric CBSCs assembled using an activated carbon as negative electrode and MWCNTs as the positive one, the addition of Ce 2 (SO 4 ) 3 moderately increases the energy density of the device (from 1.24 W h kg -1 to 5.08 W h kg -1 ). When a modified graphite felt is used as positive electrode the energy density of the cell reaches values as high as 13.84 W h kg -1 . The resultant systems become asymmetric hybrid devices where energy is stored due to double layer formation in the negative electrode and the development of the faradaic process in the positive electrode, which acts as a battery-type electrode.

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Enhanced performance of a Bi-modified graphite felt as the positive electrode of a vanadium redox flow battery

Cited by 176 publications

References 17 publications

Influence of Cr3+ concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries

Influence of Cr3+ concentration on the electrochemical behavior of the anolyte for vanadium redox flow batteries

Flowable Conducting Particle Networks in Redox-Active Electrolytes for Grid Energy Storage

Enhanced energy density of carbon-based supercapacitors using Cerium (III) sulphate as inorganic redox electrolyte

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