A Sulfonate-Functionalized Viologen Enabling Neutral Cation Exchange, Aqueous Organic Redox Flow Batteries toward Renewable Energy Storage

Abstract

Redox flow batteries using synthetically tunable and resource abundant organic molecules have gained increasing attention for large-scale energy storage. Herein we report a sulfonatefunctionalized viologen molecule, 1,1′-bis(3-sulfonatopropyl)-4,4′bipyridinium, (SPr) 2 V, as an anolyte in neutral aqueous organic redox flow batteries (AORFBs) functioning through a cation chargetransfer mechanism. Demonstrated (SPr) 2 V/KI AORFBs manifested high current performance from 40 to 100 mA/cm 2 with up to 71% energy efficiency. In extended cycling studies, the (SPr) 2 V/KI redox flow battery delivered stable cycling performance at 60 mA/cm 2 , up to 67% energy efficiency, and 99.99% capacity retention per cycle. Density functional theory modeling of the electrostatic charge surface of (SPr) 2 V and its charged state, [(SPr) 2 V] −1 , suggests charge repulsion and size exclusion enable their compatibility with a cation exchange membrane. The present findings expand the battery design of neutral viologen AORFBs and represent an attractive RFB technology for sustainable and benign renewable energy storage.

Screening Viologen Derivatives for Neutral Aqueous Organic Redox Flow Batteries

“…To prevent the dimerization, Aziz and co‐workers took advantage of coulombic repulsion, and after adding quaternary ammonium groups to the viologen core they reported a much lower capacity loss rate of 0.03 % per day for the BTMAP‐Vi/BTMAP‐Fc cell (BTMAP=bis[(3‐trimethylammonio)propyl]). A similar effect was observed for sulfonate‐functionalized viologens . The diversity in the chemical structure of viologens also enables researchers to tune the open cell voltage of the corresponding AOFBs .…”

Communication—Sulfonated Poly (ether ether ketone) as Cation Exchange Membrane for Alkaline Redox Flow Batteries

“…The typical materials of choice for these membranes are perfluorinated sulfonic acids (PFSAs), such as Nafion. One barrier that hinders their widespread adoption is their relatively high cost.10 Replacement of PFSAs with a non-fluorinated membrane could reduce the cost of the films by a factor of 2.5 and facilitate the commercial implementation of AORFBs.11 Though inspiring new AORFBs operating at neutral pH have recently been reported, 8,[12][13][14] the majority of the systems developed to date require relatively harsh operation conditions (pH>13 or pH<0). These operating parameters limit the polymer chemistry choices that warrant further exploration.…”

Red AIE‐Active Fluorescent Probes with Tunable Organelle‐Specific Targeting

“…The core molecule ( Z )‐4‐(4‐(1‐cyano‐2‐(4‐(diphenylamino)phenyl)vinyl)phenyl)pyridin‐1‐ium (CDPP) was synthesized by a two‐step reaction: i) a Knoevenagel condensation between 4‐(diphenylamino)benzaldehyde and 2‐(4‐bromophenyl)acetonitrile, followed by ii) a Suzuki coupling with 4‐pyridine boronic acid, yielding yellow powder with a total yield of 73% (Scheme S1, Supporting Information) . Finally, the targeted fluorophores CDPP‐3SO 3 , CDPP‐4SO 3 , and CDPP‐BzBr, were synthesized by simple reactions between CDPP and 1,3‐propane sultone, 1,4‐butane sultone, and 4‐bromobenzyl bromide, respectively ( Figure A; Scheme S1, Supporting Information) . The chemical structures of all the synthesized compounds were characterized by standard spectroscopic techniques such as 1 H NMR, 13 C NMR, and high‐resolution mass spectroscopy (HRMS) (Figures S1–S5, Supporting Information).…”

“…[51] Finally, the targeted fluorophores CDPP-3SO 3 , CDPP-4SO 3 , and CDPP-BzBr, were synthesized by simple reactions between CDPP and 1,3-propane sultone, 1,4-butane sultone, and 4-bromobenzyl bromide, respectively (Figure 2A; Scheme S1, Supporting Information). [51][52][53] The chemical structures of all the synthesized compounds were characterized by standard spectroscopic techniques such as 1 H NMR, 13 C NMR, and high-resolution mass spectroscopy (HRMS) (Figures S1-S5, Supporting Information).…”