Beyer K, grosse Austing J, Satola B, Di Nardo T, Zobel M, Agert C. Electrolyte Imbalance Determination of a Vanadium Redox Flow Battery by Potential-Step Analysis of the Initial Charging.
ChemSusChem 2020;
13:2066-2071. [PMID:
31967720 PMCID:
PMC7216990 DOI:
10.1002/cssc.201903485]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Vanadium redox flow batteries (VRFB) suffer from capacity fades owing to side reactions and crossover effects through the membrane. These processes lead to a deviation of the optimal initial average oxidation state (AOS=+3.5) of vanadium species in both half-cell electrolytes. To rebalance the electrolyte solutions, it is first necessary to determine the current AOS. In this study, a new method was developed that enables an accurate determination of the AOS. A potential-step analysis was performed with mixed electrolyte solutions of both half-cells during the initial charging. The potential was recorded with a simple open-circuit voltage (OCV) cell, and the potential-steps were analyzed. A correlation between the duration of the potential plateaus in the OCV and the amount of vanadium ions of a certain oxidation state in the half-cell electrolytes was found and used to precisely determine the AOS with a maximum error of 3.6 %.
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