Issue 34, 2018

Pyridyl group design in viologens for anolyte materials in organic redox flow batteries

Abstract

Organic redox compounds represent an emerging class of active materials for organic redox-flow batteries (RFBs), which are highly desirable for sustainable electrical energy storage. The structural diversity of organic redox compounds helps in tuning the electrochemical properties as compared to the case of their inorganic counterparts. However, the structural diversity makes the design and identification of redox-active organic materials difficult because it is challenging to achieve appropriate redox potential, solubility and stability together, which are the major concerns regarding the practical applicability of these materials to RFBs. Herein, we report the design, synthesis, and application of viologen molecules as anolyte materials for organic RFBs that are compatible with Li-ion electrolytes. Structural screening assisted by density functional theory (DFT) calculations suggests that the (CH2)5CH3-substituted viologen molecule exhibits reduction potential as low as 2.74 V vs. Li/Li+, good structural stability due to effective charge delocalization within the two pyridinium rings, and a solubility of up to 1.3 M in carbonate-based electrolytes. When paired with a 2,2′:6′,2′′-terpyridine–iron complex catholyte, the cell shows a high discharge voltage of 1.3–1.5 V with coulombic efficiency > 98% and energy efficiency > 84%. Both the anolyte and catholyte materials are built from earth-abundant elements and can be produced with high yields; thus, they may represent a promising choice for sustainable electrical energy storage.

Graphical abstract: Pyridyl group design in viologens for anolyte materials in organic redox flow batteries

Supplementary files

Article information

Article type
Paper
Submitted
27 mrt 2018
Accepted
09 mei 2018
First published
22 mei 2018
This article is Open Access
Creative Commons BY license

RSC Adv., 2018,8, 18762-18770

Pyridyl group design in viologens for anolyte materials in organic redox flow batteries

C. Chen, S. Zhang, Y. Zhu, Y. Qian, Z. Niu, J. Ye, Y. Zhao and X. Zhang, RSC Adv., 2018, 8, 18762 DOI: 10.1039/C8RA02641F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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