Practical and commercial issues in the design and manufacture of vanadium flow batteries

Schreiber, M.; Harrer, Martin; Whitehead, Adam; Bucsich, Herbert; Dragschitz, Matthias; Seifert, Ernst; Tymciw, Peter

doi:10.1016/j.jpowsour.2010.12.032

Cited by 61 publications

(27 citation statements)

References 7 publications

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“…• C. 60 However, the chloromethylation of SEBS did not always yield high degrees of functionalization (DF) and sometimes resulted in gelation. 54,56 The ultimate strength and the elongation at break are very important in applications where the membranes are to be assembled in electrochemical cell, wherein they are subjected to stresses that could result in deformation and mechanical failure.…”

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confidence: 99%

Anion Exchange Membranes Based on Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymers: Cation Stability and Fuel Cell Performance

Wang

Parrondo

Ramani

2017

J. Electrochem. Soc.

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A series of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS)-based anion exchange membranes (AEMs) were synthesized via chloromethylation of SEBS followed by quaternization with trimethylamine (TMA). SEBS-based AEMs functionalized with TMA + cations exhibited a hydroxide ion conductivity of 136 mS/cm at 70 • C. This membrane exhibited a phaseseparated morphology with wide and interconnected ionic channels as observed by atomic force microscopy. Poly (phenylene oxide) (PPO)-based AEMs with quaternary benzyl-trimethylammonium (TMA + ) and quaternary benzyl-tris(2,4,6-trimethoxyphenyl) phosphonium (TTMPP + ) and PPO-based AEMs with hexyl pendant chains were also synthesized and evaluated as binders in AMFC electrodes. PPO-based AEMs functionalized with TTMPP + demonstrated the best ex situ alkaline stability, losing only 9% of their ion-exchange-capacity after 30 days in 1M KOH (at 60 • C). The best in situ stability was achieved by SEBS-based MEAs (as membrane and as binder in the electrodes); The peak power density dropped approx. 35% after holding the cell at a constant voltage of 0.55V for 12 hours. Fuel cell performance with SEBS-based AEMs resulted in peak power densities of 300 mW/cm 2 at 70 • C. Anion exchange membranes (AEMs) are a promising technology for alkaline membrane fuel cells (AMFCs), 1-6 redox flow batteries (RFBs), 7-13 alkaline water electrolyzers (AWEs) [14][15][16] and reverse electrodialysis (RED) cells. 17,18 The AEMs commonly reported in peer reviewed papers mostly contain quaternary ammonium fixed cation groups, mainly in the form of benzyl trimethylammonium cations.14,19-40 However, it has been shown that quaternary ammonium-based AEMs are sensitive toward Hofmann elimination 20,41 and direct nucleophilic elimination reactions 42,43 that result in loss of ion exchange capacity (IEC) and ionic conductivity. To resolve the stability problem inherent to quaternary-ammonium-group-containing AEMs, several alternative cations, including imidazolium, 41,44,45 benzimidazolium, 3,45,46 guanidinium, 15,47,48 phosphonium 8,9,49 and metal cations 50,51 have been proposed and investigated. Phosphonium-based AEMs were investigated by Gu et al. 52 Gu et al. attached benzyl-tris(2,4,6-trimethoxyphenyl) phosphonium (TTMPP + ) onto polysulfone backbone to make AEMs, and found them to be alkaline stable; There was no ionic conductivity fade after immersion in 1M KOH for 30 days at room temperature. The bulky phosphonium-based AEMs remained stable in alkali because of the steric hindrance effect that protects the core phosphorus atom and the α-carbons against hydroxide ion attack. There is no possibility of β-elimination reaction because of the lack of hydrogen atoms in β-carbons. However, very few researchers have investigated in situ stability of bulky phosphorus-based AEMs. It is essential to correlate the ex situ stability results obtained in immersion alkaline stability tests with in situ stability in a functional H 2 /O 2 fuel cell.Hibbs 53 has shown that poly(phenylene)-bas...

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confidence: 99%

Anion Exchange Membranes Based on Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymers: Cation Stability and Fuel Cell Performance

Wang

Parrondo

Ramani

2017

J. Electrochem. Soc.

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“…• C. 35 The most commonly used cation in AEMs is the benzyl trimethylammonium cation (TMA + ). 12,34, The derivative AEMs are easy to synthesize due to the basicity of trimethylamine, which allows it to react easily with halogenated polymers through the SN 2 pathway, resulting in membranes that exhibit relatively large IECs and good ionic conductivities.…”

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confidence: 99%

Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymer Separators for a Vanadium-Cerium Redox Flow Battery

Wang

Parrondo

Ramani

2017

J. Electrochem. Soc.

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A series of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS)-based anion exchange membranes (AEMs) were synthesized via chloromethylation of SEBS followed by quaternization with trimethylamine (TMA). AEMs functionalized with TMA + cations exhibited high chloride ion conductivity of 33.6 mS/cm at 70 • C. A V-Ce RFB employing the SEBS-based AEM as the separator yielded an energy efficiency of 86% at a current density of 50 mA/cm 2 with a 10% drop in capacity over 20 charge/discharge cycles. In contrast, a V-Ce RFB using Nafion212 as the separator had an energy efficiency of 80% and a 40% drop in capacity over 20 charge/discharge cycles. The observed capacity fade was primarily due to cation intermixing between the anodic and cathodic compartments -much better permselectivity was obtained with the AEM separator. After 60 charge-discharge cycles (350 hours of operation), the ion exchange capacity and ionic conductivity of the AEM dropped by about 20%. There was no observed change in mechanical properties. The oxidative stability of the AEM was evaluated ex situ by immersion in 1.5 M VO 2 + + 3 M H 2 SO 4 for 500 hours -the ionic conductivity remained constant over this timeframe. The chemical and mechanical stability and high conductivity of SEBS-based AEMs make them promising separator candidates for electrode-decoupled RFBs. There is a growing interest in using anion exchange membranes (AEMs) as separators in alkaline membrane fuel cells (AMFCs) [1][2][3] and in other energy conversion and storage systems such as redox flow batteries (RFBs), 4-6 alkaline water electrolyzers (AWEs) 7-9 and reverse electrodialysis (RED) cells. 10RFBs are promising candidates for large-scale energy storage systems since the capacity, power and energy density parameters can be designed independently and easily modified even after installation. 11,12Original work on the iron/chromium RFB was performed by NASA researchers in 1970s. 13 Over the past few decades, several redox couples have been studied for RFB applications: All-vanadium, zinc-cerium, 23-26 and zinc-bromine. 27,28 Among these redox couples, the all-vanadium redox flow battery (VRFB) has been considered the most reliable RFB system due to its long-life and mild operating temperature range. 29 Moreover, intermixing of negative and positive electrolyte does not cause irreversible damage in the VRFB. 30 The drawbacks of VRFBs include their low standard cell voltage (1.26 V) and the relatively low solubility of vanadium salts (typically 1.5 M in common acids, such as sulfuric acid), which limit their specific capacity and energy density. 4 Besides, hydrocarbon-based membrane separators suffered from oxidative degradation caused by the vanadium (V) cation. This required the use of fluorocarbon-based membranes as separators. The expensive vanadium salts and the high cost of the fluorocarbon-based separators have limited the commercialization of VRFBs.Alternative redox species / couples could alleviate some of these issues. By using an AEM-separator, it is po...

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“…The work has recently received renewed interest and studies were made not only to the chemistry, but also to economical feasibility of this scheme (6)(7)(8)(9)(10). It was also revisited at the recent ECS meeting in Honolulu (11).…”

Section: The Vanadium Redox Cellmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy – Just One of Many Tools to Study Batteries and Power Sources

Vanýsek¹

2014

ECS Trans.

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Electrochemical Impedance Spectroscopy (EIS) is one of the many methods available to the researcher in electrochemistry. To take full advantage of its capabilities, one should understand the method and the underlying principles. In this work voltammetry on a stationary electrode, as well as with a rotated disk electrode (RDE) are presented together with EIS results, exemplified by reduction and oxidation of vanadium salts in 3 mol/l sulfuric acid. This contribution summarizes highlights, but also pitfalls of impedance measurements and their interpretation, as they are relevant to the practice and theory of electrochemical work. The most significant component in the equivalent circuit is the change transfer resistance, which matches well the voltammetric curves of the RDE experiment. A high-frequency artifact can be eliminated by formally fitting it to an inductor and resistor of series; both of these components have, however, negative value. The Oxidation States of VanadiumVanadium has extremely rich chemistry and from electrochemical point of view it is interesting because it exists in a number of different oxidation states. Most of the soluble species exist in acidic solutions so the work is usually done in sulfuric acid. The reduction from dioxovanadium(V) to vanadyl cation VO 2 + + 2 H + + e -→ VO 2+ + H 2 O E o = + 1.0 V Reduction of vanadyl to vanadium +3 VO 2+ + 2 H + + e -→ V 3+ + H 2 O E o = + 0.34 V and reduction of vanadium +3 to +2 V 3+ + e -→ V 2+ E o = -0.26 V The colors are also interesting and can guide during the experiment: VO 2 + yellow, VO 2+ blue, V 3+ green, V 2+ purple. Based on the standard potential values, it is possible to predict existence of three consecutive peaks on a cyclic voltammogram, as demonstrated in this simulation (Fig. ECS Transactions, 48 (1) 33-42 (2014) 33 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.103.160.110 Downloaded on 2015-07-06 to IP

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Practical and commercial issues in the design and manufacture of vanadium flow batteries

Cited by 61 publications

References 7 publications

Anion Exchange Membranes Based on Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymers: Cation Stability and Fuel Cell Performance

Anion Exchange Membranes Based on Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymers: Cation Stability and Fuel Cell Performance

Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene Triblock Copolymer Separators for a Vanadium-Cerium Redox Flow Battery

Electrochemical Impedance Spectroscopy – Just One of Many Tools to Study Batteries and Power Sources

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