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Title: A Highly Stable, Capacity Dense Carboxylate Viologen Anolyte towards Long‐Duration Energy Storage
Abstract

Aqueous organic redox flow batteries (AORFBs) have received increasing attention as an emergent battery technology for grid‐scale renewable energy storage. However, physicochemical properties of redox‐active organic electrolytes remain fine refinement to maximize their performance in RFBs. Herein, we report a carboxylate functionalized viologen derivative, N,N′‐dibutyrate‐4,4′‐bipyridinium,(CBu)2V, as a highly stable, high capacity anolyte material under near pH neutral conditions.(CBu)2Vcan achieve solubility of 2.1 M and display a reversible, kinetically fast reduction at −0.43 V vs NHE at pH 9. DFT studies revealed that the high solubility of(CBu)2Vis attributed to its high molecular polarity while its negative reduction potential is benefitted from electron‐donating carboxylate groups. A 0.89 V (CBu)2V/(NH)4Fe(CN)6AORFB demonstrated exceptional energy storage performance, specifically, 100 % capacity retention with a discharge energy density of 9.5 Wh L−1for 1000 cycles, power densities of up to 85 mW cm−2, and an energy efficiency of 70 % at 60 mA cm−2.(CBu)2Vnot only represents the most capacity dense viologen with pendant ionic groups and also exhibits the longest (1200 hours or 50 days) and the most stable flow battery performance to date.

 
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NSF-PAR ID:
10395210
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Angewandte Chemie
Volume:
135
Issue:
7
ISSN:
0044-8249
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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