Recent developments in organic redox flow batteries: A critical review

Leung, Puiki; Shah, Akeel A.; Sanz, Laura; Flox, Cristina; Morante, J. R.; Xu, Qian; Mohamed, Mohd Rusllim; León, Carlos Ponce de; Walsh, Frank C.

doi:10.1016/j.jpowsour.2017.05.057

Cited by 444 publications

(334 citation statements)

References 217 publications

(514 reference statements)

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“…For that purpose, surface‐buried junctions were used as photoelectrodes in both half‐reactions attaining the necessary charge voltage upon illumination (photovoltage≈1 V) in a system involving a PEC cell and a RFB. Despite the promising results, it should be pointed out that the associated cell voltage for these organic redox couples can only attain a maximum cell voltage of ≈0.89 V, which is lower than that of VRFBs …”

Section: Figurementioning

confidence: 99%

“…Despite the promising results, it should be pointed out that the associated cell voltage for theseo rganic redox couples can only attain am aximum cell voltage of % 0.89 V, which is lower than that of VRFBs. [9] One important aspectt oc onsider in the design of this kind of SPEES is the overall cell voltage required to be supplied by the semiconductor.I nterestingly,t he photocharge process in VRFBsh as only been applied to thea nodic reaction (VO 2 + /VO 2 + ), even in full-cell configuration. Although both halfreactionsh ave inherent limitations and the kinetics associated to each one strongly depends on the features of the used electrode,t he negative reaction (V 3 + /V 2 + )c an be ad etermining step because of parasitic reactions such as the hydrogen evolution reaction( HER), [10] which is kinetically more favored and might cause imbalances and decrease in performance, and because of easy reoxidationo fV 2 + under normal operating conditions.…”

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confidence: 99%

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Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

et al. 2017

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The ability of crystalline silicon to photoassist the V 3 + /V 2 + cathodic reaction under simulated solar irradiation, combined with the effect of bismuth have led to important electrochemical improvements. Besides the photovoltage suppliedb yt he photovoltaics, additional decrease in the onset potentials, high reversibility of the V 3 + /V 2 + redox pair,a nd improvement in the electrokinetics were attained thanks to the addition of bismuth. In fact, Bi 0 deposition has shown to slightly decrease the photocurrent, but the significant enhancement in the charge transfer,r eflected in the overall electrochemical performance clearly justifiesi ts use as additive in ap hotoassisted system for maximizing the efficiency of solar charge to battery.The electrical conversion and storage of solar energy is ac rucial target for assuringt he world energy supply in the long term. Because of the current maturity of the photovoltaic( PV) technology,s ystems devoted to PV electricity or to photoelectrochemical (PEC) approaches for water splitting have been strongly developed in the last years. [1,2] However,b ecause of the sluggish kineticsa ssociated to the water oxidationr eaction [3] and of inherent limitations in the H 2 economy,t he possibility of storing energy by coupling PV systems to other kind of redox pairs has recently attracted more attention, giving rise to the so-calleds olar-powered electrochemical energy storage (SPEES), [4] in which two systems, aP Va nd ab attery,a re integrated in as ingle device with potential advantages such as chargingb yusing solar light.Among other technologies, the vanadium redox flow batteries (VRFBs) are ar obust alternative to be integrated into SPEES with several advantages:d ecoupling of energy and power, use of the same elementi nb oth half-reactions and possibility of large-scale development. Previously,s ome studies reported the combination of PEC systems in VRFBs, such as TiO 2 [5] and TiO 2 / WO 3 photoanodes, [6] and CdS thin films in tandem with dyesensitized solar cells. [7] Particularly in the second case, an unbiaseds ystem reaching ap romising state of charge was achieved,a lthought he long-term stability in acid electrolyte and the low chargec urrent attained by the semitransparent CdS film were substantial limitations. These systems also have significant restraints associated to the low photon absorption in comparison to other absorbers. Crystalline silicon has also been integrated as light absorber in aq uinone/bromine biasfree redox flow battery. [8] For that purpose,surface-buried junctions were used as photoelectrodes in both half-reactionsa ttainingt he necessary charge voltage upon illumination (photovoltage % 1V)i nasystem involvingaPEC cell and aR FB. Despite the promising results, it should be pointed out that the associated cell voltage for theseo rganic redox couples can only attain am aximum cell voltage of % 0.89 V, which is lower than that of VRFBs. [9] One important aspectt oc onsider in the design of this kind of SPEES is the overall cell voltage re...

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Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

et al. 2017

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“…These salts have a potential window as wide as organic solvents. Compared with other solvents, ionic liquids have high thermal and electrochemical stability, and the conductivity is higher than aqueous electrolytes [7]. Because of these advantages, ILs have been applied to a lot of fields, such as lithium-ion batteries [8], dye-sensitized solar cells [9], electrolytes in sensors [10], electrochemical capacitors [11], lead acid batteries [12], and fuel cells [13], and even applied to flow batteries recently as electrolyte solutions [14].…”

Section: Introductionmentioning

confidence: 99%

Effects of Electrolyte Additives on Nonaqueous Redox Flow Batteries

Xu¹,

Yang²,

Su³

2020

Redox

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The widespread utilization of nonaqueous redox flow batteries is hindered by the low performance. Including some kinds of additives in electrolyte is a possible and facile solution. In this chapter, the effects of carbon dioxide gas, EC/DMC, and antimony ions on the electrochemical performance of nonaqueous redox flow batteries are disclosed. The results show that the ohmic resistance of the deep eutectic solvent (DES) electrolyte reduces significantly when adding carbon dioxide gas and EC/DMC, the percentage of reduction increases with the volume percentage of EC/ DMC in electrolyte, and the reaction kinetics almost keeps unchanged for carbon dioxide gas and EC/DMC additives. For the additive of antimony ions, the electrochemical reaction kinetics of active redox couple is enhanced, the diffusion coefficient of active ions also increases, and the charge transfer resistance decreases. The antimony ions electrodeposited on the surface of graphite felt contribute a catalytic effect on the electrochemical reaction so as to improve the performance. However, due to the trade-off between the enhanced kinetics and reduced active surface area, the optimum concentration of antimony ions is found to be 15 mM. In addition, the flow battery assembled with negative electrolyte containing antimony ions exhibits 31.2% higher power density than that of pristine DES electrolyte.

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“…Numerous systems have been reported utilizing redox-active metal salts (including the most prominent example, the vanadium RFB), organic compounds, as well as polymeric redox systems as active materials. 3,4 If this battery concept is considered under ecological points of view, multiple requirements must be met when investigating novel electrode materials. Preferably, new electrolytes feature low toxicity, high solubility, high stability upon cycling, and a low materials price.…”

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confidence: 99%

“…Subsequently, symmetrical cycling experiments revealed excellent stability at a neutral pH value for the (NH 4 ) 3 [Fe(CN) 6 ]/(NH 4 ) 4 [Fe(CN) 6 ] redox pair in a flow battery setup. The higher solubility of the ammonium salt resulted in a significantly higher initial capacity possible compared to the potassium or sodium salts.…”

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confidence: 99%

Return of the Iron Age

Schröter

Hager

Schubert

2019

Joule

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In this issue of Joule, Liu and coworkers present the use of the well-known ferrocyanide complex as an active electrode material for an aqueous organic/ organometallic redox flow battery. The ammonium cation was used as counter cation in place of the former-utilized sodium and potassium ions. Interestingly, by this simple cation exchange, remarkable capacity and cycle stability were achieved. A battery system is presented comprising ammonium ferrous hexacyanide and an organo-functionalized viologen compound.An increasing amount of energy is produced by renewables such as wind, hydro, or solar power to significantly decrease CO 2 emissions derived from the utilization of fossil fuels (i.e., coal, gas). It is expected that by 2040 over 40% of the total global energy will be produced by renewable sources. 1 Due to the nonlinear production possibilities of the renewables, the demand for innovative and ''green'' energy storage sys-tems is rising continuously as the capacities of conventional energy storage such as hydro power, thermal energy, pressurized air, or flywheel-based systems are strongly limited due to geological or physical limitations. 2 As a result, innovative new storage concepts are currently the focus of research.Redox-flow batteries (RFBs) represent an alternative approach toward con-ventional static chemical energy storage systems. This battery concept makes it possible to scale the capacity of the battery independently from the power, which is produced, once the battery has been charged. This unique characteristic is enabled by the construction principle of these electrochemical storage systems: two tanks contain an organic or aqueous solution of redox-active organic or inorganic compounds that exhibit reversible reduction and oxidation processes. The electrolyte solutions are pumped into two half-cells that are separated by a membrane and connected to an electrode each, which enables charging and current collection. The energy stored correlates to the volume of the tanks/amount of electrolyte, whereas the power scales with the size of the electrochemical cell/the cell stacks. Numerous systems have been reported utilizing redox-active metal salts (including the most prominent example, the vanadium RFB), organic compounds, as well as polymeric redox systems as active materials. 3,4 If this battery concept is considered under ecological points of view, multiple requirements must be met when investigating novel electrode materials. Preferably, new electrolytes feature low toxicity, high solubility, high stability upon cycling, and a low materials price. 5 Additionally, the desired electrolyte materials should be already commercially available or accessible through straightforward synthetic routes, enabling large-scale synthesis of the required compounds. Therefore, electrolytes comprising iron-containing compounds Figure 1. Redox Flow Battery Constructed by Liu and Coworkers Illustration of the redox flow battery that was reported by Liu and coworkers 10 to investigate the cycle stability of the synthe...

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Recent developments in organic redox flow batteries: A critical review

Cited by 444 publications

References 217 publications

Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

Role of Bismuth in the Electrokinetics of Silicon Photocathodes for Solar Rechargeable Vanadium Redox Flow Batteries

Effects of Electrolyte Additives on Nonaqueous Redox Flow Batteries

Return of the Iron Age

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