A high performance pseudocapacitive suspension electrode for the electrochemical flow capacitor

Hatzell, Kelsey B.; Beidaghi, Majid; Campos, Jonathan; Dennison, Christopher R.; Kumbur, E. Caglan; Gogotsi, Yury

doi:10.1016/j.electacta.2013.08.095

Cited by 143 publications

(129 citation statements)

References 45 publications

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“…When using ferrous salts, solutions were made under a continuous nitrogen blanket and experiments were performed with the electrolyte under a continuous nitrogen purge to mitigate the air oxidation of ferrous to ferric iron. 37,38 All tests were conducted at room temperature (20)(21)(22)(23)(24)(25) • C). It was observed that when the volume fraction of the solid particles was above some critical concentration, there was no longer enough liquid in the slurry to fully wet all of the particles.…”

Section: Methodsmentioning

confidence: 99%

“…Slurries such as these, in the absence of Faradiac current, are akin to the electrochemical flow capacitor. [20][21][22][23][24][25] Without a redox couple present, current may only pass from the electronic to the ionic phase through the charging of the double layer capacitance of the solid particles. The impedance of this interaction is described by Equation 5 and is a function of the frequency of the perturbation, ω [s …”

mentioning

confidence: 99%

“…[2][3][4][5][6][7] In the late 1970's, slurry electrodes were used in the zinc-air battery system for energy storage. [8][9][10] In the last few years, particular interest has been given to other energy storage applications, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] particularly non-aqueous lithium-ion batteries [11][12][13][14][15] and electrochemical flow capacitors. [20][21][22][23][24][25] Table I presents a brief summary of the systems studied to date.…”

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confidence: 99%

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Characterizing Slurry Electrodes Using Electrochemical Impedance Spectroscopy

Petek

Hoyt

Savinell

et al. 2015

J. Electrochem. Soc.

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Techniques for interpreting electrochemical impedance spectroscopy of different flowing slurry electrodes configurations are presented based upon models developed for macrohomogeneous porous electrodes. These models are discussed with regards to three different slurry systems; particles in deionized water, in supporting electrolyte without redox active species (akin to electrochemical flow capacitors), and in electrolytes supporting aqueous redox couples (akin to redox flow batteries). Through investigating each of these systems, the individual properties of a slurry can be determined. It was found that traditional overpotential descriptions, (ohmic, activation, and mass transfer) were insufficient to fully describe the impedance and polarization of the slurry electrodes. An overpotential due to the distributed current distribution in the slurry electrode was considered in the frequency range of activation overpotentials that depends on the exchange current density and the ratio of the electronic and ionic conductivities. In slurry electrodes made with multi-wall carbon nanotube particles supporting the ferric/ferrous redox couple, the distributed overpotential was found to be about the same order of magnitude as the activation overpotential and the total voltaic efficiency was over 80% at 200 mA/cm 2 .

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Characterizing Slurry Electrodes Using Electrochemical Impedance Spectroscopy

Petek

Hoyt

Savinell

et al. 2015

J. Electrochem. Soc.

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“…Nevertheless, there are challenges with working in non-aqueous environments and achieving satisfactory power performance (discharge rate). In contrast, the EFC utilizes lowcost, and abundant materials such as porous carbon, as the active component in aqueous solutions, 21,23 but suffers from low energy density because energy storage is limited to the available surface area. Capacitive suspension electrodes are also strong candidates for low-energy, low-concentration ion removal in applications such as capacitive deionization (desalination) and capacitive mixing (energy generation) and benefit from fast ion adsorption processes.…”

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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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“…[11] Thehit-and-run phenomenon is the basis of emergent electrochemical devices,s uch as semi-solid flow batteries and electrochemical flow capacitors, [12] while the hitand-stay phenomenon offers the possibility of modifying electrode surfaces.L iu et al [13] made use of the hit-and-stay behavior to immobilize nanoparticles from asuspension onto at ransparent electrode for electrochromic applications.W e envisioned that the hit-and-stay phenomenon could be exploited to immobilize catalyst particles suspended in an electrolyte onto an electrode to form stable catalyst films with self-healing capability.T his concept can be exploited by adding catalyst particles into the electrolyte reservoir(s) of arunning electrolyzer (see Supporting Information, Figure S1 and S2). Nickel foil was chosen as the model current collector for both the cathode and anode because of the use of Ni-based electrodes in commercial alkaline water electrolyzers.…”

Section: à2mentioning

confidence: 99%

Overcoming the Instability of Nanoparticle‐Based Catalyst Films in Alkaline Electrolyzers by using Self‐Assembling and Self‐Healing Films

et al. 2017

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Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains ac hallenge.W er eport an innovative and general approach for attaining highly stable catalyst films with selfhealing capability based on the in situ self-assembly of catalyst particles during electrolysis.The catalyst particles are added to the electrolyte forming asuspension that is pumped through the electrolyzer.P articles with negatively charged surfaces stick onto the anode,while particles with positively charged surfaces stick to the cathode.The self-assembled catalyst films have selfhealing properties as long as sufficient catalyst particles are present in the electrolyte.T he proof-of-concept was demonstrated in an on-zero gap alkaline electrolyzer using NiFe-LDH and Ni x Bc atalyst nanopowders for anode and cathode, respectively.S teady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cmLarge-scale energy storage will play an essential role in the transition from fossil-fuel-based to renewable energy owing to the intermittencyofthe energy supply by wind or the sun.

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A high performance pseudocapacitive suspension electrode for the electrochemical flow capacitor

Cited by 143 publications

References 45 publications

Characterizing Slurry Electrodes Using Electrochemical Impedance Spectroscopy

Characterizing Slurry Electrodes Using Electrochemical Impedance Spectroscopy

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

Overcoming the Instability of Nanoparticle‐Based Catalyst Films in Alkaline Electrolyzers by using Self‐Assembling and Self‐Healing Films

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