Degradation mechanisms in the non-aqueous vanadium acetylacetonate redox flow battery

Shinkle, Aaron A.; Sleightholme, Alice E.S.; Griffith, Lucas; Thompson, Levi T.; Monroe, Charles W.

doi:10.1016/j.jpowsour.2010.12.096

Cited by 118 publications

(164 citation statements)

References 35 publications

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“…In addition most RTILs exhibit negligible vapour pressures and could potentially be used in an operating device for many years without any solvent loss by evaporation. In terms of the stability of V(acac) 3 in the RTIL environment, it is known that V(acac) 3 is susceptible to ligand-substitution in the presence of water, which yields vanadyl acetylacetonate and significantly affects the reversibility of the V 2+ /V 3+ couple [29]. However, [C 2 C 1 Im][N(Tf 2 )] is hydrophobic and, if prepared carefully, usually contains ppm levels of water [26].…”

Section: Mass and Chargementioning

confidence: 99%

Room temperature ionic liquid electrolytes for redox flow batteries

Ejigu

Greatorex-Davies

Walsh

2015

Electrochemistry Communications

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Section: Mass and Chargementioning

confidence: 99%

Room temperature ionic liquid electrolytes for redox flow batteries

Ejigu

Greatorex-Davies

Walsh

2015

Electrochemistry Communications

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“…In recent literature, it has been suggested that the main reason for capacity decay in this system is chemical degradation of V(acac) 3 , however there are still uncertainties. 10,12 For example, the loss in the capacity observed here could also be due to crossover of active species Figure 5. Evolution of the relative discharge capacity with cycling for 0.1 M V(acac) 3 in a zero-gap RFB using TEA + -Nafion and Daramic separators.…”

mentioning

confidence: 93%

“…The upper cutoff potential of 2.27 V was established to minimize the formation of vanadyl acetylacetonate (VO(acac) 2 ) at the positive electrode. 10 Open circuit potentials (OCP cell ) measured for the RFB cells with TEA + -Nafion and Daramic separators were 2.17 V and 2.2 V, respectively. The OCP cell values show a 30 mV difference reflecting the different states of charge that the RFB cells reached at the end of the first charge as discussed above.…”

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confidence: 96%

“…4,17 For example, the V(acac) 3 in acetonitrile chemistry was evaluated with Neosepta AHA-AEM (Astom, Japan) in a H-type cell with charge and discharge current densities of 0.14 mA cm −2 and 0.014 mA cm −2 , respectively. 10 Columbic and energy efficiencies of ∼70% and 35%, respectively, were reported. Additionally, a non-aqueous RFB containing tri(2,2 -bypiridine) nickel (II) tetraflruoroborate (Ni(bpy) 3 (BF 4 ) 2 ) and tri(2,2 -bypiridine) iron (II) tetrafluoroborate (Fe(bpy) 3 (BF 4 ) 2 ) in propylene carbonate was studied using FAP4-AEM (FuMa Tech Co.) in a flow type cell at 0.8 mA cm −2 .…”

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confidence: 99%

“…For the TEA + -Nafion cell, even higher performance might be achieved if the electrical contact resistance was minimized between the various 3 in 0.5 M TEABF 4 /CH 3 CN at charge and discharge current density of 0.14 and 0.014 mA cm −2 , respectively. 10 battery components. The measured R HF for the cell was 5.5 times greater than that predicted from the four-point probe conductivity measurements.…”

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confidence: 99%

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Performance of a Non-Aqueous Vanadium Acetylacetonate Prototype Redox Flow Battery: Examination of Separators and Capacity Decay

Escalante-García

Wainright

Thompson

et al. 2014

J. Electrochem. Soc.

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128

119

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Non-aqueous electrolytes are stable over wide electrochemical potential windows, generally >2 V, and therefore hold promise for enabling higher energy and power density redox flow batteries (RFBs). Nevertheless, the development of non-aqueous RFBs is at an early stage and significant research efforts are needed to demonstrate non-aqueous RFBs with performance characteristics that exceed those of aqueous RFBs. The membrane or separator is a critical component that to a great extent determines the performance of RFB systems for practical applications. In this work, the performance of a RFB was evaluated with Nafion 1035 membranes and Daramic 175 SLI microporous separators. The non-aqueous electrolyte was based on vanadium (III) acetylacetonate. This chemistry possesses two couples over ∼2.2 V. Charge-discharge cycles were performed in a RFB at a current density of 10 mA cm −2 . Coulombic and energy efficiencies of 91% and 80% were achieved using the Nafion membrane. A similar RFB using the Daramic microporous separator achieved columbic and energy efficiencies of 73% and 68%, respectively. The source of capacity decay during multiple charge-discharge cycles was also investigated. The loss in the capacity was related to the poor chemical stability of the vanadium acetylacetonate in the positive electrolyte during battery cycling. Redox flow batteries (RFBs) have emerged as very attractive options for large-scale energy storage applications and, could facilitate the integration of renewable energy resources (e.g. wind and solar) with the current electricity grid.1,2 RFBs are electrochemical devices that store electrical energy in soluble electro-active species in a liquid electrolyte. The electro-active species are stored externally in separate reservoirs and are pumped through the battery stack during operation. The energy is stored or delivered by means of a redox reaction between the two species with different standard electrode potentials, separated by a membrane.2,3 Unlike conventional batteries, RFBs are more attractive for large scale energy storage because they offer more flexible operation, simple electrode reactions, longer cycle life, higher overall energy efficiencies and easier scale-up. 4 Nonetheless, RFB technology is still in an early stage; challenges that remain in the quest to produce devices with high power and energy density at low cost include the discovery or development of stable, high energy density redox electrolytes, and efficient and low cost membranes or separators. 1,5 Aqueous and non-aqueous chemistries are being investigated for use in RFBs. The cell potential of aqueous RFBs is limited to less than ∼1.6 V primarily due to the electrochemical stability of water at carbon/graphite electrodes.6 Non-aqueous solvents, on the other hand, exhibit wider electrochemical potential windows, offering the possibility for higher power and energy densities. Several non-aqueous electrolytes using metal-ligand complexes as the active-redox species in organic solvents have exhibited cell potentials ab...

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Energy Storage and Materials

Lu¹

2014

Materials in Energy Conversion, Harvesting, and Storage

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Degradation mechanisms in the non-aqueous vanadium acetylacetonate redox flow battery

Cited by 118 publications

References 35 publications

Room temperature ionic liquid electrolytes for redox flow batteries

Room temperature ionic liquid electrolytes for redox flow batteries

Performance of a Non-Aqueous Vanadium Acetylacetonate Prototype Redox Flow Battery: Examination of Separators and Capacity Decay

Energy Storage and Materials

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