Multi−Functional Gradient Fibrous Membranes Aiming at High Performance for Both Lithium–Sulfur and Zinc–Air Batteries
Round 1
Reviewer 1 Report
In this work, the authors have shown good ideas in the preparation of muti-functional gradient fibrous membranes of Co-N-C/PVDF/PAN and PVDF/PAN for use as an active site in Li-sulfur and Zn-air battery, respectively. The authors show characterization results to indicating specific morphology and composite structure of the gradient fibrous membranes. However, I think there is still a lot of critical analysis lacking, so it is advisable for the authors to add more results. The authors should make major revision to this research based on the recommendations below for consideration before publication.
1. The author should add some table to comparing this work with the same previous research for clarified that the research can be improved performance of Li-sulfur and Zn-air battery.
2. In DFT analysis, the author may consider to adding absorption energies results of Co-N-C with LiPSs namely Li2S8, Li2S6, and Li2S4 and comparison with N-C to clarify that Co-N-C more interaction with LiPSs than N-C.
3. The author should consider add TGA results to confirm the content percentage of S loading in the Co-N-C membrane.
4. In figure 3e and g, the author should consider use the same line color of the same sample, for example the specific capacity and coulombic efficiency of Co-N-C/PVDF/PAN should same color line.
5. The wettability property of cathode material in Zn-air battery is important to confirm a better charge transfer between the cathode surface and the electrolyte. The author may consider add contact angle results of Co-N-C comparison with N-C and explain more detail for confirm that Co-N-C has optimized wettability for use as a cathode in Zn-air battery.
Author Response
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Reviewer 2 Report
The authors developed muti-functional gradient fibrous membranes via the electrospinning method, which was used in Li-S and Zn-air batteries. The Li-S batteries with the rationally designed membranes achieved high areal capacity with high sulfur loading. Binder-free cathodes in Zn-air battery were also demonstrated using the Co-N-C/PVDF membranes. Overall, the work can be published after minor revisions. 1) what is the BET area for these designed membranes? The authors claimed that the high specific surface area of Co metal accelerates the dynamics (should be kinetics?) of oxidation-reduction and improves active species utilization in rechargeable batteries (Page 2, lines 91-93) 2) In Figure 3a and 3c, the S@Co-N-C/PVDF/PAN/Li showed lower resistance and overpotentials. However, the S@Co-N-C/PAN/Li showed the lowest overpotential among the three samples, which is inconsistent with the results from Figures 3a and 3c. It would be great if the authors could elaborate on it. 3) Figures 3e and 3g are not clear. Please revise them with clear labels for capacities and CE. 4) It would be great to have the CV comparison of Co-N-C and N-C electrodes in Figure 4a. 5) It is hard to get detailed information on the cycling stability curves in Figure 5e. The authors should provide several cycles of charge/discharge profiles (from Figure 5e) with details in SI.Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The authors present muti-functional gradient fibrous membranes aiming to high-performance both lithium-sulfur and zinc-air battery, , which is an interesting work. The work was logically discussed and explained. Thus, I recommend this work to publish after Minor Revision. Some suggestions are as follows:
1. Please pay attention to the use of capitalization in the title. According to SEM information, Co-N-C is called nanosheets rather than fibers, please check it.
2. Could the authors explain the reason regarding difference in ID/IG ratio of Co-N-C and N-C?
3. The specific capacity and cycle performance are suggested to be compared with previous reports, for example a table is added.
4. Could the authors explain the fluctuations for this curve of Zn mass-normalized specific capacities in Figure 5d.
5. The relevant literature such as Small, 2020, 16(4), 1906458 and Journal of Materials Chemistry A 2020, 8, 24053-24064 and ACS nano 2021, 15: 18931-18973 should be considered for a solid background.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
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