Redox‐Flow‐Batterien: von metallbasierten zu organischen Aktivmaterialien

Winsberg, Jan; Hagemann, Tino; Janoschka, Tobias; Hager, Martin D.; Schubert, Ulrich S.

doi:10.1002/ange.201604925

Cited by 102 publications

(41 citation statements)

References 190 publications

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“…[6] One of the most promising research topics has been the replacement of the problematic vanadium compounds by organic redox molecules that are abundant, low cost, and environmental friendly. [7] Some pioneering examples include organic RFBs based on quinoid-type redox couples in acid [8] and alkaline electrolytes. [9] Another encouraging research line is the substitution of aqueous electrolytes by non-aqueous electrolytes [10] or even ionic liquids, [11] which are more electrochemically stable and would allow achieving higher battery voltages and energy densities.…”

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confidence: 99%

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

et al. 2017

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Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short‐lifetimes, and expensive ion‐selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane‐free battery that relies on the immiscibility of redox electrolytes and where vanadium is replaced by organic molecules. We show that the biphasic system formed by one acidic solution and one ionic liquid, both containing quinoyl species, behaves as a reversible battery without any membrane. This proof‐of‐concept of a membrane‐free battery has an open circuit voltage of 1.4 V with a high theoretical energy density of 22.5 Wh L−1, and is able to deliver 90 % of its theoretical capacity while showing excellent long‐term performance (coulombic efficiency of 100 % and energy efficiency of 70 %).

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confidence: 99%

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

et al. 2017

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“…All three compounds exhibit faster diffusion and have larger rate constants than most inorganic compounds and are on par with organic compounds applied in ARFBs. 6,[8][9][10][11][12][13]39 Regarding the physical and chemical properties of these two-electron storage molecules, they are promising anolyte candidates for AORFBs using a Cl À exchange mechanism. 40 mA/cm 2 to 100 mA/cm 2 at increments of 20 mA/cm 2 ( Figures 4A-4C).…”

Section: Scheme 1 Synthesis Of Two-electron Storage Viologen Moleculesmentioning

confidence: 99%

“…and achieve sustainable and ''green'' electrochemical energy storage. 6,7 Given that resource-abundant redox-active organic molecules have been advocated to replace inorganic materials in traditional RFBs, recently, aqueous organic RFBs (AORFBs) and nonaqueous organic RFBs (NAORFBs) have received increasing attention as viable alternatives. Besides the general technical merits of RFBs discussed above, AORFBs have several outstanding advantages for large-scale energy storage, five of which are outlined here.…”

Section: Introductionmentioning

confidence: 99%

“…30,31 On the other hand, NAORFBs are claimed to have higher cell voltages and higher energy densities by avoiding the water-splitting voltage window seen in aqueous electrolytes. 6,31 However, compared with AORFBs, NAORFBs encounter several major technical challenges for practical applications, four of which are outlined here. 10 (1) The use of flammable organic solvents not only is a safety concern but also adds additional capital costs.…”

Section: Introductionmentioning

confidence: 99%

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Designer Two-Electron Storage Viologen Anolyte Materials for Neutral Aqueous Organic Redox Flow Batteries

Debruler

Moss

et al. 2017

Chem

310

335

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Liu and co-workers reported a series of rationally designed two-electron storage viologen molecules as anolytes for high-voltage and high-power pH-neutral aqueous organic redox flow batteries. The synthetic and computational chemistry presented has opened a new avenue for designing energy-dense redox-active organic molecules for building neutral AORFBs with high power density and high energy density, and it promises economical, benign, and widespread uses of redox flow batteries in large-scale energy storage. HIGHLIGHTSTwo-electron storage viologens were designed for energy-storage applications Neutral aqueous organic redox flow batteries up to 1.38 V and 130 mW/cm 2 An integrated approach of synthesis, electrochemistry, and computational modelling Molecular engineering is a powerful strategy for developing redox-active molecules DeBruler et al., Chem 3, 961-978 December 14, 2017 ª SUMMARYAqueous organic redox flow batteries (AORFBs) are highly attractive for largescale energy storage because redox-active organic molecules are synthetically tunable, sustainable, and potentially low cost. Here, we show that rational molecular engineering yielded a series of two-electron storage viologen molecules as anolyte materials for AORFBs. In neutral NaCl solutions, these viologen anolytes have a theoretical capacity of up to 96.5 Ah/L in H 2 O and exhibit a reduction potential as low as À0.78 V versus normal hydrogen electrode. The neutral aqueous flow batteries with two two-electron storage viologen molecules delivered a cell voltage of up to 1.38 V and outstanding battery performance, including a power density of up to 130 mW/cm 2 , capacity retention of up to 99.99% per cycle, and energy efficiency of up to 65% at 60 mA/cm 2 . Density functional theory calculations revealed that the 1e À and 2e À reduced redox states of these molecules were stabilized by the high charge delocalization of their frontier SOMO or HOMO.

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“…With ideal electron-accepting capability,v iologens have seen successo ver the years, implemented in smallo rganic radical batteries( ORBs;F igure 11)a nd more recently,i no rganic redox flow batteries (ORFBs). [48]…”

Section: Organic Batteriesmentioning

confidence: 99%

Viologens and Their Application as Functional Materials

Striepe

Baumgartner

2017

Chemistry A European J

263

235

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Organic materials have recently gained considerable attention for electronic applications, improving performance and sustainability to current technologies. Commercialized metal-based systems are generally expensive, toxic and difficult to recycle, however organic materials offer promising solutions. Viologens, N,N' di-quaternized bipyridyl salts, are a well-studied species exhibiting three reversible redox states, possessing valuable electrochromic and electron-accepting properties. These properties can be fine-tuned through synthesis by altering the nitrogen substituents and various counteranions. Currently, viologens have become of great interest as functional materials in a wide array of applications; a few to name include electrochromic devices, molecular machines, and organic batteries. This review highlights representative recent work and advances towards utilizing viologens in practical applications that currently compete with metal-based technologies. Additionally, modified viologens that can be further fine-tuned will be discussed.

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Redox‐Flow‐Batterien: von metallbasierten zu organischen Aktivmaterialien

Cited by 102 publications

References 190 publications

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

A Membrane‐Free Redox Flow Battery with Two Immiscible Redox Electrolytes

Designer Two-Electron Storage Viologen Anolyte Materials for Neutral Aqueous Organic Redox Flow Batteries

Viologens and Their Application as Functional Materials

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