Tetrabutylammonium hexafluorophosphate and 1-ethyl-3-methyl imidazolium hexafluorophosphate ionic liquids as supporting electrolytes for non-aqueous vanadium redox flow batteries

Zhang, David; Liu, Qinghua; Shi, Xiaosong; Li, Yongdan

doi:10.1016/j.jpowsour.2011.10.136

Cited by 74 publications

(57 citation statements)

References 15 publications

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“…7,12,16 The low areal resistance of separators employed in our investigations allowed higher charge-discharge current densities (by up to 70-fold, 10 mA cm −2 ) while obtaining an enhancement of two-fold in the voltaic efficiencies (VE) as shown in Table II. On average, the iR HF loss was 60 mV and 20 mV for the TEA + -Nafion and Daramic separator, respectively, as compared to 470-500 mV measured for BF 4 − -Neosepta at 1 mA cm −2 .…”

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confidence: 85%

“…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.…”

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confidence: 94%

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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.

126

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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mentioning

confidence: 85%

mentioning

confidence: 94%

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.

126

119

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“…[ 87 -89 ] An ionic liquid also was recently reported for RFB application by Li et al, using tetrabutylammonium hexafl uorophosphate (TEAPF 6 ) and 1-ethyl-3-methyl imidazolium hexafl uorophosphate (EMIPF 6 ) as the supporting electrolytes of a non-aqueous RFB based on vanadium acetylacetonate (V(acac) 3 ) active species. [ 90 ] With the presently reported research, the solubility of the active species is still the major concern. Extensive matrix work is required to identify the suitable redox couple and supporting electrolyte solution offering high solubility and stability in a high operational voltage window.…”

Section: Feature Articlementioning

confidence: 99%

Recent Progress in Redox Flow Battery Research and Development

Wang

Luo

et al. 2012

Adv Funct Materials

1,333

930

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With the increasing need to seamlessly integrate renewable energy with the current electricity grid, which itself is evolving into a more intelligent, efficient, and capable electrical power system, it is envisioned that energy‐storage systems will play a more prominent role in bridging the gap between current technology and a clean sustainable future in grid reliability and utilization. Redox flow battery technology is a leading approach in providing a well‐balanced solution for current challenges. Here, recent progress in the research and development of redox flow battery technology, including cell‐level components of electrolytes, electrodes, and membranes, is reviewed. The focus is on new redox chemistries for both aqueous and non‐aqueous systems.

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“…V(acac) 3 at the H-type cell showed a charging and discharging potential of 2.75 V and 0.4 V, respectively, where the discharge potential difference was affected by the electrode distance. 7,37 Similar H-type cells used for the Mn(acac) 3 and Cr(acac) 3 redox flow battery in AN showed a huge potential difference between charging and discharging, including ohmic and IR resistance, according to electrode distance. 38,39 Another possibility could be the dissociation of the V(acac) 3 complex to V(acac) 2 or the formation of a V(V) oxidation state or vanadium crossover.…”

Section: Resultsmentioning

confidence: 99%

Na-β-Alumina as a Separator in the Development of All-Vanadium Non-Aqueous Tubular Redox Flow Batteries: An Electrochemical and Charging-Discharging Examination Using a Prototype Tubular Redox Flow Cell

Muthuraman

Boyeol

Moon

2018

J. Electrochem. Soc.

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The non-aqueous redox flow battery (N-ARFB) is in the development stages with aim to produce high power density storage systems. In addition to the development of N-ARFBs, this study examined the applicability of a sodium beta alumina (Na-β-Al 2 O 3 ) membrane in the development of a N-ARFB through an analysis of the electrochemical processes, redox active species migration, and charging/discharging at room temperature (25 ± 3 • C). Through impedance analysis, the ionic conductivity of the Na-β-Al 2 O 3 was 2.97 × 10 −2 S cm −1 which is slightly higher than the literature value. UV-Visible analysis showed no migration of the vanadium acetylacetonate (V(acac) 3 ) ion from one compartment to another, either during the charging or discharging process. In addition, the lack of a change in the morphology of the spent membrane revealed not only stability, but also confirmed no permeation of V(acac) 3 species. The maximum applied current density for charging and discharging was 0.01 mA cm −2 and 0.0015 mA cm −2 , respectively. The charging/discharging of V(acac) 3 enables voltage and current efficiencies of almost 16% and 11% respectively, at the state of charge of 15%. This demonstrates that the Na-β-Al 2 O 3 membrane can be improved for use in N-ARFB after optimizing the conditions. © The Author The non-aqueous redox flow battery (N-ARFB) is in the development stages with the strong potential for high power density (>2 V) N-ARFB that can store energy from non-conventional sources, such as wind mills and solar power. 1 Although the development of N-ARFBs has attracted considerable interest, such as redox active species selection, 2 electrolyte development, 2,3 and solvent selection, 4 the identification of a suitable membrane is one of the crucial factors because of the crossover of redox active species. [4][5][6] The oxidation state of most redox active metal organic complexes (RAMOCs) is negative, which means that there is theoretically less migration on membranes with the same polarity but the transport of oppositely charged negative ions is allowed. Using this approach, many anionic selective polymeric membranes (AEM) were developed and made commercially available for N-ARFBs, such as Neosepta AHA (Astom, Japan), FAP4 (FuMaTech Co.), and AMI-7001 (Membrane International Inc., USA), which were investigated in N-ARFB systems using a conventional H-type cell. [7][8][9] On the other hand, they showed poor chemical and mechanical stability in organic electrolytes. 1 Through a zero-gap (electrodes coated on the membrane) redox flow battery prototype design, the modified Nafion 1035 membrane could be operated in all VRFB with columbic and energy efficiencies of 91% and 80%, respectively. 10 A polymeric membrane prepared by a simultaneous polymerization and quarternization method showed low vanadium permeability while retaining good dimensional and chemical stability in N-ARFB. 11 In addition to crosslinking, a pore-filled polyvinyl chloride (PVC) AEM exhibited high ion conductivity and V(III)(acetylacetonate) 3 (V(acac) ...

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Tetrabutylammonium hexafluorophosphate and 1-ethyl-3-methyl imidazolium hexafluorophosphate ionic liquids as supporting electrolytes for non-aqueous vanadium redox flow batteries

Cited by 74 publications

References 15 publications

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

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

Recent Progress in Redox Flow Battery Research and Development

Na-β-Alumina as a Separator in the Development of All-Vanadium Non-Aqueous Tubular Redox Flow Batteries: An Electrochemical and Charging-Discharging Examination Using a Prototype Tubular Redox Flow Cell

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