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Title: Multifaceted effects of ring fusion on the stability of charged dialkoxyarene redoxmers
Due to their almost unlimited scalability, redox flow batteries can make versatile and affordable energy storage systems. Redox active materials (redoxmers) in these batteries largely define their electrochemical performance, including the life span of the battery that depends on the stability of charged redoxmers. In this study, we examine the effects of expanding the π-system in the arene rings on the chemical stability of dialkoxyarene redoxmers that are used to store positive charge in RFBs. When 1,4-dimethoxybenzene is π-extended to 1,4-dimethoxynaphthalene, a lower redox potential, improved kinetic stability, and longer cycling life are observed. However, when an additional ring is fused to make 9,10-dimethoxyanthracene, the radical cation undergoes rapid O-dealkylation possibly due to increased steric strain that drives methoxy out of the arene plane thus breaking the π-conjugation with O 2p orbitals. On the other hand, the planar structure of 1,4-dimethoxynaphthalene may facilitate second-order reactions of radical cations leading to their neutralization in the bulk. Our study suggests that extending the π-system changes reactivity in multiple (sometimes, opposite) ways, so lowering the oxidation potential through π-conjugation to improve redoxmer stability should be pursued with caution.  more » « less
Award ID(s):
2055222 2436843
PAR ID:
10611021
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Editor(s):
Belharouak, Ilias
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of Power Sources
Volume:
608
Issue:
C
ISSN:
0378-7753
Page Range / eLocation ID:
234689
Subject(s) / Keyword(s):
Nonaqueous redox flow battery organic redox molecules Ring fusion Stability Steric strain
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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