New Mass Transport Correlation for Vanadium Redox-Flow Batteries Based on a Model-Assisted Parameter Estimation
Round 1
Reviewer 1 Report
The manuscript reported a 2D mathematical model for developing a new mass transport correlation for a SGL GFD4.6A carbon felt applied in VRFB under realistic flow conditions. Detailed investigation of electrolyte properties, impedance spectroscopic characterization for evaluation of kinetic properties and the use of potential probe signals to identify the overpotential of positive and negative electrode are carried out prior to mass transport parameter estimation by comparison of model and experi-mental data. The model validation yields a good agreement between predicted and experimental data with the following new and reliable mass transport equation.
I consider the content of this manuscript will definitely meet the reading interests of the readers of the Batteries journal. However, there are certain English spelling and grammar issues, and also the discussion and explanation should be further improved.
Therefore, I suggest giving a minor revision and the authors need to clarify some issues or supply some more experimental data to enrich the content. This could be comprehensive and meaningful work after revision.
Detailed comments can be found in the PDF file.
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Author Response
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Reviewer 2 Report
1. As a review article, the manuscript references appear to be thin, so it is suggested to increase the number of references and cite the latest literatures. For example: 10.1021/acssuschemeng.2c01372, 10.1016/j.est.2021.103526, 10.1016/j.est.2022.106191
2. What is the significance of the new mass transport correlation developed in this review?
3. In Figure 4, the label column of the horizontal axis has marked the percent sign of SOC, and the percent sign after the number can be omitted. The same problem appears in Figure 5 and Figure 6.
4. The author set up 6 groups of different flow rate conditions in Figure 10, the maximum flow rate reached 491mL/min, whether this flow rate can be achieved in practical applications, and at the same time, too high flow rate will have a great impact on the performance of the battery, how did the author take this into consideration.
5. What is the basis for determining the range of maximum and minimum Reynolds numbers of the experiment in Figure 2, and is there any reference support?
6. Should there be a precondition for setting the current density at the electrode-bipolar plate interface, the membrane-electrode interface to zero, and no mass transfer through the membrane or bipolar plate?
7. In the second figure of Figure S1, when the state of charge of the cathode and anode is different and the flow rate is different, the flow rate of the anode is set to 22 mL/min, which is different from the flow rate of 23 mL/min in the other four figures. Is it 23mL/min for both? The second graph of Figure S2 is also the same question, whether the negative flow rate is 68ml/min or not. The same problem occurs in the second diagram of Figures S5, S7, and the sixth diagram of Figure S8.
Author Response
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Reviewer 3 Report
This is a well-written manuscript on mass transport effects in flow batteries. The model used is an extension of existing theoretical treatments and is verified by means of a body of experimental data. It might be useful to consider stationary measurements (e.g. double-half cells with varying flow rates and concentrations) where effects of SOC are absent.
Author Response
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Reviewer 4 Report
In this work a two dimensional mathematical model is applied to develop a new mass transport correlation for a SGL GFD carbon felt applied in a 100 cm² single cell vanadium redox-flow battery under realistic flow conditions.
The available literature was thoroughly reviewed to identify a basis for the mass transport correlation and to reduce the number of parameters that needed revision, to just one the Sherwood correlation coefficient aSh.
A two-dimensional model was designed based on literature approaches to describe the electrode processes and all the required input parameters were taken from evaluation described in previous work or were determined experimentally in-situ or ex-situ. The model validation yields a good agreement between predicted and experimental data with the following new and reliable mass transport equation.
Overall strengths:
(+) The paper is well-written.
(+) The problem is important.
(+) The problem is well-defined.
(+) The literature review is good.
(+) The references are appropriate.
(+) The proposed method is well-explained.
(+) The method is innovative.
(+) The experiments are convincing.
(+) The experiments can be replicated.
(+) The figures are appropriate.
Weaknesses:
(-) Novelty is unclear.
(-) The introduction must be improved.
(-) Some improvements are needed in the description of the method.
Contributions should be highlighted more. It should be made clear what is novel and how it addresses the limitations of prior work. It is important to clearly explain what is new and what is not in the proposed solution.
Author Response
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Reviewer 5 Report
1. Title is not impressive. It should be modified.
2. The authors can use abbreviations in the revised manuscript (for example:- vanadium redox flow battery - VRFB, Vanadium species - VS).
3. The demonstrated VRFB information (Practical scale - in various industries and academics ) must be included in the introduction section.
4. The authors can improve the introduction section using the relevant research/review article from the MDPI batteries
Author Response
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Round 2
Reviewer 2 Report
It can be published.
