Person: Fell, Eric
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Fell
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Eric
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Fell, Eric
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Publication Near Neutral pH Redox Flow Battery with Low Permeability and Long‐Lifetime Phosphonated Viologen Active Species(Wiley, 2020-04-06) Jin, Shijian; Fell, Eric; Vina-Lopez, Lucia; Jing, Yan; Michalak, Winston; Gordon, Roy; Aziz, MichaelA highly stable phosphonate‐functionalized viologen is introduced as the redox‐active material in a negative potential electrolyte for aqueous redox flow batteries (ARFBs) operating at nearly neutral pH. The solubility is 1.23 m and the reduction potential is the lowest of any substituted viologen utilized in a flow battery, reaching −0.462 V versus SHE at pH = 9. The negative charges in both the oxidized and the reduced states of 1,1′‐bis(3‐phosphonopropyl)‐[4,4′‐bipyridine]‐1,1′‐diium dibromide (BPP−Vi) effect low permeability in cation exchange membranes and suppress a bimolecular mechanism of viologen decomposition. A flow battery pairing BPP−Vi with a ferrocyanide‐based positive potential electrolyte across an inexpensive, non‐fluorinated cation exchange membrane at pH = 9 exhibits an open‐circuit voltage of 0.9 V and a capacity fade rate of 0.016% per day or 0.00069% per cycle. Overcharging leads to viologen decomposition, causing irreversible capacity fade. This work introduces extremely stable, extremely low‐permeating and low reduction potential redox active materials into near neutral ARFBs.Publication A High Voltage Aqueous Zinc–Organic Hybrid Flow Battery(Wiley, 2019-05-17) Park, Minjoon; Beh, Eugene S.; Fell, Eric; Jing, Yan; Kerr, Emily; De Porcellinis, Diana; Goulet, Marc‐Antoni; Ryu, Jaechan; Wong, Andrew A.; Gordon, Roy; Cho, Jaephil; Aziz, MichaelWater‐soluble redox‐active organic molecules have attracted extensive attention as electrical energy storage alternatives to redox‐active metals that are low in abundance and high in cost. Here an aqueous zinc–organic hybrid redox flow battery (RFB) is reported with a positive electrolyte comprising a functionalized 1,4‐hydroquinone bearing four (dimethylamino)methyl groups dissolved in sulfuric acid. By utilizing a three‐electrolyte, two‐membrane configuration this acidic positive electrolyte is effectively paired with an alkaline negative electrolyte comprising a Zn/[Zn(OH)4]2− redox couple and a hybrid RFB is operated at a high operating voltage of 2.0 V. It is shown that the electrochemical reversibility and kinetics of the organic redox species can be enhanced by an electrocatalyst, leading to a cyclic voltammetry peak separation as low as 35 mV and enabling an enhanced rate capability.Publication The Poor Academic’s DC-Offset for Reversing Polarity in Electrochemical Cells: Application to Redox Flow Cells(The Electrochemical Society, 2022-09-01) Amini, Kiana; Fell, Eric; Aziz, MichaelWe provide a simple and inexpensive manual DC-offset method for extending the accepted voltage range of a battery cycler to negative voltages, without interfering with the actual operation of the electrochemical cell under the test or exceeding the voltage specs of the battery cycler instrument. We describe the working principles of the method and validate the proposed setup by operating short-term and long-term redox flow battery cycling using compositionally symmetric cell, with open-circuit voltage of zero, and full cell configurations. The method can be used to extend the capability of battery cycler instrumentation to operate any electrochemical cell that requires the polarity to be reversed during operation. Applications include cycling of other symmetric cells (e.g., Li-ion cells), implementation of polarity reversal steps for rejuvenation of electroactive species or rebalancing electrochemical cells, and alternating polarity for electrochemical synthesis.Publication Highly Stable, Low Redox Potential Quinone for Aqueous Flow Batteries(Wiley, 2022-02-24) Wu, Min; Bahari, Meisam; Jing, Yan; Amini, Kiana; Fell, Eric; George, Thomas; Gordon, Roy; Aziz, MichaelAqueous organic redox flow batteries are promising candidates for large-scale energy storage. However, the design of stable and inexpensive electrolytes is challenging. Here, we report a highly stable, low redox potential, and potentially inexpensive negolyte species, sodium 3,3′,3′′,3′′′-((9,10-anthraquinone-2,6-diyl)bis(azanetriyl))tetrakis(propane-1-sulfonate) (2,6-N-TSAQ), which is synthesized in a single step from inexpensive precursors. Pairing 2,6-N-TSAQ with potassium ferrocyanide at pH=14 yielded a battery with the highest open-circuit voltage, 1.14 V, of any anthraquinone-based cell with a capacity fade rate <10 %/yr. When 2,6-N-TSAQ was cycled at neutral pH, it exhibited two orders of magnitude higher capacity fade rate. The great difference in anthraquinone cycling stability at different pH is interpreted in terms of the thermodynamics of the anthrone formation reaction. This work shows the great potential of organic synthetic chemistry for the development of viable flow battery electrolytes and demonstrates the remarkable performance improvements achievable with an understanding of decomposition mechanisms.Publication Extremely Stable Anthraquinone Negolytes Synthesized from Common Precursors(Elsevier BV, 2020-06) Wu, Min; Jing, Yan; Wong, Andrew; Fell, Eric; Jin, Shijian; Tang, Zhijiang; Gordon, Roy; Aziz, MichaelSynthetic cost and long-term stability remain two of the most challenging barriers for the utilization of redox-active organic molecules in redox flow batteries for grid scale energy storage. Starting from potentially inexpensive 9,10-dihydroanthracene, we developed a new synthetic approach for two extremely stable anthraquinone negolytes, i.e., 3,3'-(9,10- anthraquinone-diyl)bis(3-methylbutanoic acid) (DPivOHAQ) and 4,4'-(9,10- anthraquinone-diyl)dibutanoic acid (DBAQ). Pairing with a ferrocyanide posolyte at pH 12, DPivOHAQ and DBAQ can transfer up to 1.4 M and 2 M electrons with capacity fade rates of 0.014%/day and 0.0084%/day, respectively, and exhibit 1.0 V of open circuit voltage. By adjusting the supporting electrolytes to pH 14, DPivOHAQ exhibited a record low capacity fade rate of <1%/year. We attribute the capacity loss of these flow batteries to be caused primarily by the formation of anthrone, which can be suppressed by increasing the pH of the electrolyte and reversed by exposure to air.Publication In situ Electrosynthesis of Anthraquinone Electrolytes in Aqueous Flow Batteries(Royal Society of Chemistry (RSC), 2020-09-02) Jing, Yan; Wu, Min; Wong, Andrew A.; Fell, Eric; Jin, Shijian; Pollack, Daniel; Kerr, Emily; Gordon, Roy; Aziz, MichaelWe demonstrate the electrochemical oxidation of an anthracene derivative to a redox-active anthraquinone at room temperature in a flow cell without the use of hazardous oxidants or noble metal catalysts. The anthraquinone, generated in situ, was used as the active species in a flow battery electrolyte without further modification or purification. This potentially scalable, safe, green, and economical electrosynthetic method is also applied to another anthracene-based derivative and may be extended to other redox-active aromatics.Publication Functioning Water‐insoluble Ferrocenes for Aqueous Organic Flow Battery via Host-Guest Inclusion(Wiley, 2020-12-09) Li, Yuanyuan; Xu, Ziang; Liu, Yahua; Jin, Shijian; Fell, Eric; Wang, Baoguo; Gordon, Roy; Aziz, Michael; Yang, Zhengjin; Xu, TongwenFerrocene (Fc) is one of the very limited organic catholyte options for aqueous organic flow batteries (AOFBs), a potential electrochemical energy storage solution to the intermittency of renewable electricity. Commercially available Fc derivatives are barely soluble in water, while existing methods for making water‐soluble Fc derivatives by appending hydrophilic or charged moieties are tedious and time‐consuming, with low yields. Here, a strategy was developed based on host–guest inclusion to acquire water‐soluble Fc‐based catholytes by simply mixing Fc derivatives with β‐cyclodextrins (β‐CDs) in water. Factors determining the stability and the electrochemical behavior of the inclusion complexes were identified. When adopted in a neutral pH AOFB, the origin of capacity loss was identified to be a chemical degradation caused by the nucleophilic attack on the center FeIII atom of the oxidized Fc derivatives. By limiting the state of charge, a low capacity fade rate of 0.0073 % h−1 (or 0.0020 % per cycle) was achieved. The proposed strategy may be extended to other families of electrochemically active water‐insoluble organic compounds, bringing more electrolyte options for practical AOFB applications.Publication Molecular Engineering of an Alkaline Naphthoquinone Flow Battery(American Chemical Society (ACS), 2019-07-11) Tong, Liuchuan; Goulet, Marc-Antoni; De Porcellinis, Diana; Kerr, Emily; Fell, Eric; Aspuru-Guzik, Alan; Gordon, Roy; Aziz, Michael; Tabor, DanielAqueous organic redox flow batteries (AORFBs) have recently gained significant attention as a potential candidate for grid-scale electrical energy storage. Successful implementation of this technology will require redox-active organic molecules with many desired properties. Here we introduce a naphthoquinone dimer, bislawsone, as the redox-active material in a negative potential electrolyte (negolyte) for an AORFB. This novel dimerization strategy substantially improves the performance of the electrolyte vs. that of the lawsone monomer in terms of solubility, stability, reversible capacity, permeability and cell voltage. An AORFB pairing bislawsone with a ferri/ferrocyanide positive electrolyte delivers an open-circuit voltage of 1.05 V and cycles at a current density of 300 mA/cm2 with a negolyte concentration of 2 M electrons in alkaline solution. We determined the degradation mechanism for the naphthoquinone-based electrolyte using chemical analysis, and predict theoretically electrolytes based on naphthoquinones that will be even more stable.