Non-aqueous chromium acetylacetonate electrolyte for redox flow batteries

Liu, Qinghua; Shinkle, Aaron A.; Li, Yongdan; Monroe, Charles W.; Thompson, Levi T.; Sleightholme, Alice E.S.

doi:10.1016/j.elecom.2010.09.013

Cited by 196 publications

(202 citation statements)

References 15 publications

Supporting

Mentioning

188

Contrasting

Unclassified

Order By: Relevance

“…[7]. It is interesting to note that the irreversibility of each couple (indeed the entire response, ignoring the fact that we cannot directly compare potentials due to the use of different reference electrodes) mirrors that recorded in acetonitrile, and may be attributable to ligand loss upon oxidation/reduction [7].…”

Section: ) Measurement Of Lewis Basicities (And Gutmann Donor Numbementioning

confidence: 95%

“…Organic electrolytes often have wider potential windows than that of water and, consequently, there is a lot of interest in high energy density, organic RFB systems and systems based on Ru [4], V [5], Mn [6], and Cr [7] complexes have been reported. In a similar approach to that used in the popular aqueous all-vanadium RFBs [8], the same chemical species is often used on each side of non-aqueous RFBs, mitigating the effects of transfer of redox species between compartments and increasing the coulombic efficiency [3].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Room temperature ionic liquid electrolytes for redox flow batteries

Ejigu

Greatorex-Davies

Walsh

2015

Electrochemistry Communications

View full text Add to dashboard Cite

show abstract

Section: ) Measurement Of Lewis Basicities (And Gutmann Donor Numbementioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Room temperature ionic liquid electrolytes for redox flow batteries

Ejigu

Greatorex-Davies

Walsh

2015

Electrochemistry Communications

View full text Add to dashboard Cite

show abstract

“…Nonaqueous RFB cells based on several metal/organic coordination complexes have been hypothesized to charge and discharge via single-electron disproportionation and comproportionation mechanisms, respectively, 2,3,6,8,9 but the chromium system exhibits unexpected charge/discharge behavior in light of this proposed electrochemistry. The present study aims to illuminate the chemical or electrochemical processes responsible for the unusual cycling responses of Cr(acac) 3 cells.…”

Section: 21mentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

“…When supported by alkali and alkaline-earth-metal salts, the cations coordinate with acac -ligands harvested from the M(acac) 3 and shift equilibrium reduction potentials; this coordination does not occur in the presence of tetraethylammonium cations, however. 16,23,24 Tetraalkylammonium salts have consequently been preferred as supporting electrolytes for nonaqueous RFB research.Nonaqueous RFB cells based on several metal/organic coordination complexes have been hypothesized to charge and discharge via single-electron disproportionation and comproportionation mechanisms, respectively, 2,3,6,8,9 but the chromium system exhibits unexpected charge/discharge behavior in light of this proposed electrochemistry. The present study aims to illuminate the chemical or electrochemical processes responsible for the unusual cycling responses of Cr(acac) 3 cells.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

Saraidaridis

Bartlett

Monroe

2016

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

Chromium acetylacetonate, or Cr(acac) 3 , is a promising active species for high-energy-density symmetric redox flow batteries because the neutral complex supports multiple charge-transfer reactions with widely separated redox potentials. Voltammetric and spectroelectrochemical measurements were performed to probe the mechanism of the first electrochemical disproportionation of Cr(acac) 3 -i.e., the cell reaction associated with the two redox couples immediately adjacent to the equilibrium potential of a freshly prepared nonaqueous Cr(acac) 3 solution. Substantially different limiting currents are observed for the positive and negative half-reactions, suggesting that at least one deviates from the similar outer-sphere single-electron transfer mechanisms proposed earlier. Spectroelectrochemical chronoamperometry suggests ligand dissociation in the negative reaction, and consequent structural reorganization of the Cr(acac) 3 complex. Vanadium acetylacetonate was investigated for comparison, and no ligand dissociation was observed. A negative half-reaction mechanism consistent with the voltammetric and spectroelectrochemical data is proposed, and used to rationalize observations of charge/discharge behavior in cycling Cr (acac) As researchers have identified the economic benefits that largescale energy storage delivers to the grid, research into redox flow batteries (RFBs) has expanded.1 In efforts to increase energy density or decrease active-species loading, researchers have targeted nonaqueous RFB chemistries, which can produce operating potentials outside the stability window of water.2-8 Several nonaqueous chemistries are based on transition-metal-centered coordination complexes. 2,3,[6][7][8][9] Chromium acetylacetonate, or Cr(acac) 3 , appears especially promising as an RFB active species: it has five accessible redox states, and there is a wide voltage separation between the first reduced and first oxidized states of the neutral complex. The Cr(acac) 3 complex has also been used for catalysis 10 and as a standard for atomic absorption spectra.11 Whereas vanadium acetylacetonate, or V(acac) 3 , appears to support outer-sphere electron transfer for both single-electron addition and withdrawal in certain nonaqueous electrolytes, and to undergo both charge exchanges with relatively facile kinetics, 12 the voltammetric response of Cr(acac) 3 is harder to interpret. Experimental efforts to clarify the electrochemistry of Cr(acac) 3 have been challenging because the reaction mechanism apparently varies with the choices of solvent, supporting electrolyte, and working electrode. 13-17The literature describing nonaqueous Cr(acac) 3 electrochemistry does not provide a consensus about the mechanisms for either the first reduction or first oxidation of the neutral complex. The electrochemical response during reduction depends heavily upon solvent, with different behavior observed in dimethylsulfoxide, 13,15,18,19 N,N-dimethylformamide, 15 dichloromethane, 14 acetonitrile, 15,17,20 and others. 15 Various mechanisms have...

show abstract