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Assessment methods and performance metrics for redox flow batteries

Nature Energy volume 6, pages 582–588 (2021)Cite this article

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Abstract

Redox flow batteries (RFBs) are a promising technology for large-scale energy storage. Rapid research developments in RFB chemistries, materials and devices have laid critical foundations for cost-effective and long-lasting RFB systems. However, the lack of consistency in testing methods and assessment metrics makes it challenging to compare reported RFBs and evaluate their potential for practical applications. Here we discuss RFB assessment methods and performance metrics in direct relation to their working principles and degradation mechanisms. We first introduce basic cell attributes and performance metrics and describe common misconceptions in testing and performance comparison. We discuss major RFB decay mechanisms and highlight bottlenecks in organic, inorganic and solid-hybrid RFBs. Testing protocols, reporting practices and comparison criteria are proposed under a general framework of symmetric and asymmetric full RFBs. These recommendations can be broadly applied to a wide range of flow battery chemistries to facilitate future benchmarking and RFB development.

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Fig. 1: Fundamental illustrations of RFBs.
Fig. 2: Role of areal capacity and SOC in RFB testing and summary of reported RFBs.
Fig. 3: Recommended testing protocols and data analysis of three major RFB cell testing configurations.

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Acknowledgements

The work described herein was supported by a grant from the Research Grant Council (RGC) of the Hong Kong Special Administrative Region, China (project number T23-601/17-R).

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Authors and Affiliations

  1. Electrochemical Energy and Interfaces Laboratory, Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong SAR, China

    Yanxin Yao, Jiafeng Lei, Yang Shi, Fei Ai & Yi-Chun Lu

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Correspondence to Yi-Chun Lu.

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Peer review information Nature Energy thanks Travis Anderson, Mike Perry and Wei Wang for their contribution to the peer review of this work.

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Source Data Fig. 2

Numerical data used to generate the graphs in Fig. 2c,d.

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Yao, Y., Lei, J., Shi, Y. et al. Assessment methods and performance metrics for redox flow batteries. Nat Energy 6, 582–588 (2021). https://doi.org/10.1038/s41560-020-00772-8

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