Radiation-grafted copolymers for separation and purification purposes: Status, challenges and future directions

Nasef, Mohamed Mahmoud; Güven, Olgun

doi:10.1016/j.progpolymsci.2012.07.004

Cited by 240 publications

(101 citation statements)

References 395 publications

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“…Amidoximes are vanadium complexing groups, 17,29,30 yet are shown here to provide effective vanadium barrier properties in the membrane under low pH conditions.…”

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Bifunctional Ion-Conducting Polymer Electrolyte for the Vanadium Redox Flow Battery with High Selectivity

Nibel

Schmidt

Gubler

2016

J. Electrochem. Soc.

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The need for electrochemical energy storage increases along with the growing share of fluctuating renewables for power generation. The all-vanadium redox flow battery (VRB) has experienced increasing attention in this context. Its electrolyte membrane is a key component, yet currently perfluorinated materials (e.g., Nafion) are mainly used in VRBs, which have neither been designed for this particular application, nor are they cost-effective. The cross-over of redox active vanadium species impairs cell efficiency, in particular in case of thin Nafion membranes with low ohmic resistance. Here, we present a potentially generic concept of a bifunctional ion-conducting membrane prepared by radiation grafting with sulfonic acid proton exchange sites and amidoxime moieties. The crossover of vanadium-ions is reduced four-fold in the presence of amidoxime groups without markedly impairing the conductivity of the membrane. A VRB cell containing such membrane shows increased energy efficiency and negligible capacity fading over 122 charge / discharge cycles compared to cells with Nafion membrane, which showed a loss of discharge capacity of around 35% after 35 cycles and considerable electrolyte imbalance. The growing need for energy and urge to reduce CO 2 emissions require clean and renewable energy sources, such as wind and solar power.1-3 Since these primary energies are inherently intermittent, 4 the development of adequate energy storage scenarios is essential. 5,6Among the various energy storage concepts, batteries have been shown to be especially promising. 7,8 Batteries for grid-scale energy storage require good cycling stability, rapid response to changes, high roundtrip efficiency and reasonable lifecycle costs.Redox flow batteries (RFBs) can fulfill these requirements 9 to target applications in the MW to GW power scale with typical charge/ discharge times of 4 to 6 h. 10 Key advantages over conventional rechargeable grid-scale batteries, such as Na-S batteries, are the independent scalability of energy and power, inherent safety, deep discharge capability and low self-discharge. 7,11,12 A redox flow battery consists of two external tanks filled with liquid electrolyte and a stack of cells that contain porous electrodes separated by an ion exchange membrane (IEM). The IEM avoids cross-mixing of redoxactive species and allows the transport of background electrolyte ions. The all-vanadium redox flow battery (VRB) is the most advanced type.13 VRBs use the same redox-active element on the negative and positive electrode, preventing irreversible cross-contamination of the electrolytes.14 The membrane is a key cost driver in a VRB system and can account for the major share of the stack cost. 15 An ideal membrane for an RFB should have low crossover of redox-active species and water, low cost, high conductivity, and high chemical stability in the respective electrolyte solution. 16Depending on the nature of the exchange groups, IEMs are generally classified into cation and anion exchange membranes (CEMs, AEMs). Variou...

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“…Amidoximes are vanadium complexing groups, 17,29,30 yet are shown here to provide effective vanadium barrier properties in the membrane under low pH conditions.…”

mentioning

confidence: 96%

“…28 Herein we present a potentially generic design concept of a bifunctional membrane for VRB applications containing protogenic styrene sulfonic acid and amidoxime groups. Amidoximes are vanadium complexing groups, 17,29,30 yet are shown here to provide effective vanadium barrier properties in the membrane under low pH conditions.…”

mentioning

confidence: 96%

Bifunctional Ion-Conducting Polymer Electrolyte for the Vanadium Redox Flow Battery with High Selectivity

Nibel

Schmidt

Gubler

2016

J. Electrochem. Soc.

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“…All binding energies (BEs) were referenced to the C1s hydrocarbon peak at 286.4 eV. Spectra were analyzed using XPSPEAK software Akashi and Kuroda -eXPRESS Polymer Letters Vol.9, No.1 (2015) [2][3][4][5][6][7][8][9][10][11][12][13] . Curve fitting of the high resolution spectra used 30% Gaussian/70% Lorentzian mixed line shapes for each component.…”

Section: Xps Measurementmentioning

confidence: 99%

“…The spectrum of the plasma-treated PES membrane contained a weak absorption band at approximately 1700 cm -1 (Figure 2 curve b). The spectrum of the PES-g-PAA membrane appeared with a strong car- Akashi and Kuroda -eXPRESS Polymer Letters Vol.9, No.1 (2015) [2][3][4][5][6][7][8][9][10][11][12][13] bonyl (C=O) stretching absorption band at 1705 cm -1 (Figure 2 curve c). This indicates that polyacrylic acid chains were successfully grafted on the membrane.…”

Section: Sem Measurementmentioning

confidence: 99%

“…High capacity membranes have been developed for the biotechnology industry with varying pore size distributions, such as isotropic and anisotropic structures [9]. In recent years, many functionalized membranes with surface modifications have been reported [10][11][12]. There has been significant interest in using affinity membrane chromatography for bioprocessing, but few reports are applied in production scales because the adsorption capacities of the affinity membranes are relatively low compared with those for conventional bead chromatography [13].…”

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