Electrochemical Properties of Organic Liquid Electrolytes Based on Quaternary Onium Salts for Electrical Double‐Layer Capacitors

Ue, Makoto; Ida, K.; Mori, Shoichiro

doi:10.1149/1.2059270

Cited by 329 publications

(244 citation statements)

References 2 publications

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“…The selection of the lithium salt, in conjunction with the PC solvent, offered a particularly low conductivity since lithium salts typically afford 2-4× lower conductivities than quaternary ammonium salts, regardless of the solvent. 46 Table I quantifies the conductivities and viscosities of the 4 different redox active electrolyte compositions investigated, where 0.5 M TEATFSI in MeCN serves as a low viscosity and high conductivity supporting electrolyte and 0.5 M LiTFSI in PC serves as a high viscosity and low conductivity supporting electrolyte. Additionally, a prior study has reported the conductivity of dry SGL 25AA carbon paper, under 20% compression, to be 2200-2700 mS cm −1 .…”

Section: Resultsmentioning

confidence: 99%

Towards Low Resistance Nonaqueous Redox Flow Batteries

Milshtein

Barton

Carney

et al. 2017

J. Electrochem. Soc.

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Nonaqueous redox flow batteries (NAqRFBs) are a promising, but nascent, concept for cost-effective grid-scale energy storage. While most studies report new active molecules and proof-of-concept prototypes, few discuss cell design. The direct translation of aqueous RFB design principles to nonaqueous systems is hampered by a lack of materials-specific knowledge, especially concerning the increased viscosities and decreased conductivities associated with nonaqueous electrolytes. To guide NAqRFB reactor design, recent techno-economic analyses have established an area specific resistance (ASR) target of <5 cm 2 . Here, we employ a state-of-the-art vanadium flow cell architecture, modified for compatibility with nonaqueous electrolytes, and a model ferrocene-based redox couple to investigate the feasibility of achieving this target ASR. We identify and minimize sources of resistive loss for various active species concentrations, electrolyte compositions, flow rates, separators, and electrode thicknesses via polarization and impedance spectroscopy, culminating in the demonstration of a cell ASR of ca. 1.7 cm 2 . Further, we validate performance scalability using dynamically similar cells with a ten-fold difference in active areas. This work demonstrates that, with appropriate cell engineering, low resistance nonaqueous reactors can be realized, providing promise for the cost-competitiveness of future NAqRFBs. Grid-scale energy storage has emerged as a critical technology for alleviating the intermittency of renewables, 1 improving the efficiency of the existing grid infrastructure, and offering frequency or voltage regulation.2 Redox flow batteries (RFBs) are particularly attractive storage devices for energy-intensive grid applications.2,3 In a typical RFB, charge-storing active species are dissolved in liquid electrolytes, which are housed in large and inexpensive tanks. The electrolytes are pumped through a power-generating electrochemical reactor, where the active species undergo reduction or oxidation on the surfaces of porous electrodes to charge or discharge the battery. [3][4][5][6] This unique architecture offers several advantages over conventional battery systems, including decoupled power and energy scaling, long operational lifetimes, easy maintenance, simplified manufacturing, and high active-to-inactive materials ratio (particularly at long storage durations). Despite many attractive features, state-of-the-art RFBs are currently too expensive for widespread adoption.7 While the majority of RFB electrolytes are aqueous, 6 transitioning to nonaqueous chemistries could enable higher cell potentials via wider electrolyte stability windows, subsequently increasing the electrolyte energy density and reducing chemical costs. 6,[8][9][10][11] Furthermore, the use of nonaqueous solvents enables a broader palette of potentially inexpensive active materials, which could significantly lower RFB costs. 7,12 In contrast to their aqueous counterparts, nonaqueous redox flow batteries (NAqRFBs) are a nascent technology,...

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Section: Resultsmentioning

confidence: 99%

Towards Low Resistance Nonaqueous Redox Flow Batteries

Milshtein

Barton

Carney

et al. 2017

J. Electrochem. Soc.

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“…Although five isomers are conceivable, only three could be unambigu- Ref. [22] ously identified via 11 B NMR. The chemical shifts of the different isomers are very similar and the corresponding signals overlapping.…”

Section: Resultsmentioning

confidence: 99%

“…depending on the length of the alkyl chains) [22]. The conductivity of 1 M solutions of the azolylborate salts in acetonitrile is summarized in Table 2 and compared to 1 M TEABF.…”

Section: Resultsmentioning

confidence: 99%

Azolylborates for Electrochemical Double Layer Capacitor Electrolytes

Francke

Cericola

Kötz

et al. 2011

Zeitschrift Für Physikalische Chemie

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Azolylborate / Alkylammonium Salt / Electrochemical Double Layer Capacitor / Supporting Electrolyte / Cyclic VoltammetryAsymmetric tetraalkylammonium salts of azolylborates were synthesized and studied with respect to their suitability as supporting electrolytes in electrochemical double layer capacitors. In contrast to current conducting salts used in this device, azolylborates exhibit an excellent stability towards thermal load and moisture. In addition to good conductivity and stability towards cathodic reduction we found certain limitations when more positive potentials were applied.

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“…This quantity depends strongly on the electrolyte conductivity and its viscosity. Based on the experimental investigations reported in [16][17][18] the dependency of the electrolyte conductivity k as a function of its temperature can be described by the following equation:…”

Section: Sc Ageing Processes Description At Macroscopic Levelmentioning

confidence: 99%

Modelling of current and temperature effects on supercapacitors ageing. Part I: Review of driving phenomenology

Torregrossa

Paolone

2016

Journal of Energy Storage

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The paper proposes a study of the phenomenology driving the ageing mechanisms of electrochemical double layer supercapacitors (SCs) during their most common operating conditions. In particular, the paper focuses on the so-called life endurance (LE) and power cycling (PC) stresses. The paper first provides a description of the variables governing the SC behaviour at the microscopic scale (i.e., porosity of the electrode surface, diffusion and conductivity of the electrolyte). Then, the paper discusses the link between these variables and the ones describing the SC behaviour at the macroscopic scale (i.e., temperature of the electrolyte and delivered current). This analysis is applied to both LE and PC stresses and as well as to their combination. The discussions make reference to experimental results obtained at the Author's laboratory by means of a dedicated test bench.

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Electrochemical Properties of Organic Liquid Electrolytes Based on Quaternary Onium Salts for Electrical Double‐Layer Capacitors

Cited by 329 publications

References 2 publications

Towards Low Resistance Nonaqueous Redox Flow Batteries

Towards Low Resistance Nonaqueous Redox Flow Batteries

Azolylborates for Electrochemical Double Layer Capacitor Electrolytes

Modelling of current and temperature effects on supercapacitors ageing. Part I: Review of driving phenomenology

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