Distinct performance evaluation of a direct methanol SPE fuel cell. A new method using a dynamic hydrogen reference electrode

Küver, A.; Vogel, Israel; Vielstich, W.

doi:10.1016/0378-7753(94)01943-6

Cited by 119 publications

(57 citation statements)

References 3 publications

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“…Furthermore, there is a Donnan potential across the membrane due to the difference in proton activities across both half-cells. [22] Therefore, the full description of the open-circuit potential (OCP) for the VRFB can be formulated as the following:…”

Section: Mathematical Modelmentioning

confidence: 99%

In Situ Potential Distribution Measurement and Validated Model for All-Vanadium Redox Flow Battery

Gandomi

Aaron

Zawodzinski

et al. 2015

J. Electrochem. Soc.

100

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An in situ, local potential measurement technique was further developed and applied to all-vanadium redox flow batteries to determine the potential distribution within multilayer electrodes of the battery. Micro-scale potential probes enabled in situ measurement of local potential in electrode layers between the cell flow field and membrane. The local redox potentials were recorded for different operating conditions and states of charges. To further analyze the behavior of potential distribution in the through-plane direction, a mathematical model was developed and the species distribution as well as the flux density of any individual component was modeled in terms of contributions from convective, diffusive and electrophoretic fluxes at each operating condition. Good agreement was achieved between the mathematical model prediction and experimental data with maximum error of 8%. Both mathematical simulation and experimental data confirmed the distribution of potential in the through plane direction as a function of discharge current density, predicting the lowest potential in a region close to the flow plate. Redox flow batteries have many benefits including energy efficiency, capital cost, and life cycle costs compared with other gridscale energy storage technologies.1 Multiple chemistries have been developed for redox flow batteries such as iron-chromium, 2 allvanadium, 3 bromine-polysulfide 4 and zinc-bromine. 5 Among these many chemistries, the all-vanadium redox flow battery (VRFB) has been studied in great detail and is relatively mature with several fullsize systems in operation around the world. The VRFB employs the V (I I )/V (I I I ) redox couple at the negative side and the V (I V )/V (V ) redox couple at the positive side, in the form of V O 2+ and V O + 2 . The kinetics associated with reduction and oxidation of vanadium species are known to be very complex 6,7 In this paper, the following simplified set of global half-reactions are adopted for the negative and positive electrodes.One advantage of VRFBs is that in utilizing the same element, vanadium, as active species in both negative and positive electrolytes, crossover of active species does not foul the electrolyte, and results only in decreased coulombic efficiency. Storage capacity can be regained through electrolyte rebalancing. The VRFB also has a wide operating temperature range from −5 • C to 50• C 8 and fast response (around 350 μs) for start-up and switching between charging and discharging processes, using a sulfuric and hydrochloric acid mixture. 9Cost is still the major barrier to VRFB commercialization. Zhang et al.10 estimated that the cell stack is one of the highest cost components with 31% of capital cost from a base case VRFB. One way to decrease the stack cost is to increase the power density of the VRFB during charge-discharge cycles, allowing for smaller stacks for the same power.11 In order to achieve high power density, the cells should operate at high current density with decreased polarization losses (activation, ohmic an...

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Section: Mathematical Modelmentioning

confidence: 99%

In Situ Potential Distribution Measurement and Validated Model for All-Vanadium Redox Flow Battery

Gandomi

Aaron

Zawodzinski

et al. 2015

J. Electrochem. Soc.

100

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“…A Hg/Hg 2 SO 4 reference electrode (C3 Prozess -und Analysentechnik GmbH) was connected to the cell in an 'edge-type' configuration in which an extension of the Nafion 117 membrane was placed in contact with the reference electrode used in the cell. [29][30][31] The junction region was kept hydrated with a 2 M H 2 SO 4 solution.…”

mentioning

confidence: 99%

Performance of Different Carbon Electrode Materials: Insights into Stability and Degradation under Real Vanadium Redox Flow Battery Operating Conditions

Nibel

Taylor

Pătru

et al. 2017

J. Electrochem. Soc.

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This work focuses on the performance and stability of selected commercial carbon electrode materials before and after heat-treatment in an operating all-vanadium redox flow battery (VRB). Heat treatment results in improved cell performance for all tested materials, with SGL 39 AA carbon papers and SIGRACELL GFD4.6 EA carbon felt showing the best performance. Further investigation of these two materials by in situ reference electrode measurements reveal improvements after heat-treatment that originate mainly from the negative electrode or V 2+ /V 3+ side of the cell. Upon extended cycling, carbon felt is found to be stable. Carbon papers however, show significant performance losses originating from the negative electrode side. The potential limit during charging and the exposure to very negative potentials appears to be a critical issue at the negative electrode in the VRB. Analysis of both materials after cycling by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy reveal significant differences in their surface chemistry, structure and morphology. These differences give valuable insights into the behavior and degradation of different carbon materials used in VRBs. Redox flow batteries (RFBs) are a promising technology for efficient energy storage and grid stabilization.1,2 The all-vanadium redox flow battery (VRB), which uses vanadium ions in different oxidation states at the positive and negative electrodes, is the most advanced RFB to date.3 The electrodes are a crucial component of the VRB, as they provide the surface on which the respective electrochemical reactions occur. Thus, catalytic activity, wettability and mass transport properties of the electrodes strongly affect VRB performance. Ideal electrodes for the VRB should provide both: long term durability and stable catalytic activity. Various materials have been considered as electrodes for the use in VRBs including non-carbon based dimensionally stable anode electrodes and carbon based electrodes such as carbon felt, carbon paper, carbon nanotubes, carbon nanofibers or graphene oxides. 4 To enhance electrochemical activity and wettability of carbon based materials in VRBs, different surface modification methods have been used. Carbon electrodes have been coated with metals such as iridium, 5 doped with nitrogen 6 or decorated with nanomaterials such as graphene-nanowalls 7 or graphite carbon nanotubes. Most of these surface treatment approaches introduce functional groups, commonly oxygen onto the carbon electrode surface. This leads to increased wettability and redox activity, which is generally attributed to the increased concentration of surface-active oxygen functional groups.11 Among the various surface modifications, heattreatment is still regarded as the most common and facile approach to incorporate oxygen groups onto the surface of carbon materials. 4 In an effort to better understand the role of oxygen functional groups on electrode performance, Fink et al. studied pristine and heat-treated Rayon (a regene...

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“…(Zhang et al, 2007, Tang et al, 2007, Lindermeir et al, 2004. However, the CL prepared in CCE method cannot be effectively transferred to the membrane during the course of hot-pressing the MEA due to the change of the structure in the CL (a distribution of ionomer and porosity) and the dehydration of the membrane, which may lead to an irreversible performance loss of the MEA (Kuver et al, 1994).…”

Section: Catalyst Coated On Electrode Methods (Cce)mentioning

confidence: 99%

High Performance Membrane Electrode Assemblies by Optimization of Processes and Supported Catalysts

Pak¹,

You²,

Choi³

et al. 2012

Hydrogen Energy - Challenges and Perspectives

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Distinct performance evaluation of a direct methanol SPE fuel cell. A new method using a dynamic hydrogen reference electrode

Cited by 119 publications

References 3 publications

In Situ Potential Distribution Measurement and Validated Model for All-Vanadium Redox Flow Battery

In Situ Potential Distribution Measurement and Validated Model for All-Vanadium Redox Flow Battery

Performance of Different Carbon Electrode Materials: Insights into Stability and Degradation under Real Vanadium Redox Flow Battery Operating Conditions

High Performance Membrane Electrode Assemblies by Optimization of Processes and Supported Catalysts

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