Issue 16, 2022

Metal-free polypeptide redox flow batteries

Abstract

Non-aqueous organic redox flow batteries (NAORFBs) are considered emerging large-scale energy storage systems due to their larger voltage window as compared to aqueous systems and their metal-free nature. However, low solubility, sustainability, and crossover of redox materials remain major challenges for the development of NAORFBs. Here, we report the use of redox active α-helical polypeptides suitable for NAORFBs. The polypeptides exhibit less crossover than small molecule analogs for both Daramic 175 separator and FAPQ 375 PP membrane, with FAPQ 375 PP preventing crossover most effectivley. Polypeptide NAORFBs assembled with a TEMPO-based polypeptide catholyte and viologen-based polypeptide anolyte exhibit low capacity fade (ca. 0.1% per cycle over 500 cycles) and high coulombic efficiency (>99.5%). The polypeptide NAORFBs exhibit an output voltage of 1.1 V with a maximum capacity of 0.53 A h L−1 (39% of the theoretical capacity). After 500 charge–discharge cycles, 60% of the initial capacity was retained. Post cycling analysis using spectral and electrochemical methods demonstrate that the polypeptide backbone and the ester side chain linkages are stable during electrochemical cycling. Taken together, these polypeptides offer naturally-derived, deconstructable platforms for addressing the needs of metal-free energy storage.

Graphical abstract: Metal-free polypeptide redox flow batteries

Supplementary files

Article information

Article type
Paper
Submitted
02 May 2022
Accepted
11 Jul 2022
First published
12 Jul 2022
This article is Open Access
Creative Commons BY-NC license

Mater. Adv., 2022,3, 6558-6565

Metal-free polypeptide redox flow batteries

Z. Liang, T. P. Nguyen, N. H. Attanayake, A. D. Easley, J. L. Lutkenhaus, K. L. Wooley and S. A. Odom, Mater. Adv., 2022, 3, 6558 DOI: 10.1039/D2MA00498D

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