Hierarchical Two-Dimensional Layered Nickel Disulfide (NiS2)@PEDOT:PSS Nanocomposites as Battery-Type Electrodes for Battery-Type Supercapacitors with High Energy Density
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Editor and Authors:
Hierarchical Two-Dimensional Layered Nickel Disulfide 2 (NiS2)@PEDOT:PSS Nanocomposites as BaĴery-Type 3 Electrodes for SupercapaĴeries with High Energy Density
Overall, this work is well-written (although it needs some improvements) and has good amount of electrochemical data it deserves to be considered for publication in Electrochem. However, in my opinion, there are some important information that are missing and I can only recommend its acceptance after these issues be properly addressed. Before I recommend its acceptance, some points must be clarified and a major revision is needed.
Some other issues that need to be addressed are:
1. The abstract should present in a concise manner the main outcome of the paper while stating the main hypothesis behind the work. The current abstract should be polished along this line. Please bear in mind that a sharp abstract is central for article visibility.
2. The main problem statement and justification for the research has not been clearly stated. In introduction, clearly build your research hypothesis (straightforward question that is answerable by yes or no). I am not sure this is clear in the manuscript. It is not clear the contribution of the manuscript to the empirical literature.
3. The introduction should contain 4 or 5 paragraphs. The second paragraph is too long.
4. Synthesis of Two-Dimensional Layered Nickel Disulfide 2 (NiS2)@PEDOT:PSS Nanocomposites. A Proposed synthesis of mechanism for the materials preparation should be shown and proper explained. I recommend this be made in one figure explained each step, this could easily helpt the readers in understand this work.
5. The quality of the Figure 1b is very bad. Please, replace it for a better one.
6. It would be very interesting if the authors insert the mapping of the elements (EDS analysis). This would help to see the dispersion of the main elements on the electrode structure. The amount of each element should also be taken into account.
7. What about the specific surface area and porosity of the materials? It is well know that pore structure play an important on the electrochemical properties.
8. The other consideration is about to make a comparison, in a table, highlighting the main device metrics/findings in the literature with the metrics/findings of this manuscript.
9. Conclusion: the conclusion should summarize the main findings and clarify how the results presented in the paper have made the field progress, for instance in comparison with other works. Future perspectives and research directions should also be included. A sole summary of the findings is not sufficient. Please polish the conclusion along this view.
Author Response
Comment-1: The abstract should present in a concise manner the main outcome of the paper while stating the main hypothesis behind the work. The current abstract should be polished along this line. Please bear in mind that a sharp abstract is central for article visibility.
Answer: Thank you for your comment. As per your comment, we have modified the abstract in a concise manner that comprising the main outcome of the paper in the revised manuscript.
Comment-2: The main problem statement and justification for the research has not been clearly stated. In introduction, clearly build your research hypothesis (straightforward question that is answerable by yes or no). I am not sure this is clear in the manuscript. It is not clear the contribution of the manuscript to the empirical literature.
Answer: Thank you for your comment. As per your comment, we have modified our introduction section by including main problem statement and justification for the research in the revised manuscript.
Comment-3: The introduction should contain 4 or 5 paragraphs. The second paragraph is too long.
Answer: Thank you for your comment. The introduction section consists of literature reviews of recently published articles that reveals the significance of PEDOT:PSS in transition metal sulfide performance. As per your suggestion, we have modified the Introduction section with 4 paragraphs.
Comment-4: Synthesis of Two-Dimensional Layered Nickel Disulfide 2 (NiS2)@PEDOT:PSS Nanocomposites. A Proposed synthesis of mechanism for the materials preparation should be shown and proper explained. I recommend this be made in one figure explained each step, this could easily help the readers in understand this work.
Answer: Thank you for your comment. As per your comment, we have incorporated the schematic representation of NiS2@PEDOT:PSS nanocomposite in the revised manuscript as Figure 1 (Page No. 4).
Comment-5: The quality of the Figure 1b is very bad. Please, replace it for a better one.
Answer: Thank you for your comment. As per your comments, we have modified this image and it is given as Figure 1b in the revised manuscript.
Comment-6: It would be very interesting if the authors insert the mapping of the elements (EDS analysis). This would help to see the dispersion of the main elements on the electrode structure. The amount of each element should also be taken into account.
Answer: Thank you for your comment. As per your comments, we have provided the EDX mapping for NiS2 synthesized by microwave-hydrothermal method as Figure 1d-e.
Comment-7: What about the specific surface area and porosity of the materials? It is well known that pore structure plays an important on the electrochemical properties.
Answer: Thank you for your comment. In the case of EDLCs, the surface area is an important parameter to determine the electrochemical performance. But in the case of battery-type hybrid electrodes, the surface area is not a determining parameter. Since NiS2 exhibits battery-type charge storage (diffusion-controlled), the surface area study is not carried out.
Comment-8: The other consideration is about to make a comparison, in a table, highlighting the main device metrics/findings in the literature with the metrics/findings of this manuscript.
Answer: Thank you for your valuable suggestion. As per your suggestion, we have incorporated a table (Table 1) that clearly depicts the main device metrics/findings with the literature in the revised manuscript (Page No.14).
Comment-9: Conclusion: the conclusion should summarize the main findings and clarify how the results presented in the paper have made the field progress, for instance in comparison with other works. Future perspectives and research directions should also be included. A sole summary of the findings is not sufficient. Please polish the conclusion along this view.
Answer: Thank you for your comment. As per your comment, we have summarized the main findings, field progress and future perspectives in the conclusion part.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors present interesting paper in the field of electrochemistry. Unfortunately, the paper is a bit sloppily edited.
I have the following comments:
* What is the specific surface area of the presented material (m^2/g) in the Figure 1? Please provide an approximate value.
* Figure 1 - the font in the description of each marker in the photos is a different size. 500 nm, 5 µm, 10 µm, 100 µm should have the same font size.
* EIS, Nyquist and Figure 2 - The interpretation of the results is very modest. Based on the characteristics from Fig. 2, no values were determined in the equivalent circuit diagram of the proposed electrode.
* Figure 9 e. The authors show an experiment with an LED. The photo is incorrectly described (inside the photo) - the description says LED on the left and right side. There are not two LEDs there. The tested cells are on the left and the LED on the right.
Author Response
Comment-1: What is the specific surface area of the presented material (m^2/g) in the Figure 1? Please provide an approximate value.
Answer: Thank you for your comment. In the case of EDLCs, the surface area is an important parameter to determine the electrochemical performance. But in the case of battery-type hybrid electrodes, the surface area is not a determining parameter. Since NiS2 exhibits battery-type charge storage (diffusion-controlled), the surface area study is not carried out.
Comment-2: Figure 1 - the font in the description of each marker in the photos is a different size. 500 nm, 5 µm, 10 µm, 100 µm should have the same font size.
Answer: Thank you for your comment. We have provided the same font size for all images.
Comment-3: EIS, Nyquist and Figure 2 - The interpretation of the results is very modest. Based on the characteristics from Fig. 2, no values were determined in the equivalent circuit diagram of the proposed electrode.
Answer: Thank you for your comment. As per your comment, we given an interpretation of the EIS results with equivalent circuit diagram and its series resistances are provided in the revised manuscript (Page No.6).
Comment-4: Figure 9e. The authors show an experiment with an LED. The photo is incorrectly described (inside the photo) - the description says LED on the left and right side. There are not two LEDs there. The tested cells are on the left and the LED on the right.
Answer: Thank you for your correction. Please note that we have provided a clear description for the same in the revised manuscript (Page No. 14).
Reviewer 3 Report
Comments and Suggestions for AuthorsIn this manuscript, the author synthesized NiS2@PEDOT:PSS nanocomposite electrodes which demonstrated characteristics of both supercapacitors and batteries. In addition to finding the optimal PEFOT:PSS concentration for electrode fabrication, the authors also made the asymmetrical supercapattery and tested the energy density and power density. I think this work fits well with the scope of electrochem journal. However, the following comments need to be addressed before final publication.
1. In the Experimental Section, the author mentioned XRD, TEM and EDS were performed to characterize the electrodes but I did not see them in the results. Can the authors provide the data and discussion, since these data are important to demonstrate the hierarchical structure?
2. Have the authors done SEM (or maybe XRD and TEM) on the NiS2@PEDOT:PSS made with different PEDOT:PSS concentration? I think the authors can elaborate on this as the data could explain why the authors saw reduced performance in the electrodes made with high PEDOT:PSS concentration.
3. The authors need to provide more references in support of their discussion. For examples, all the equations used in the manuscript, and the explanation of total charge distribution in NPS1 electrode, etc.
4. In Figure 3b, what exactly contributed to the increased anodic current in NPS1 material? Have the authors scanned the electrodes with multiple cycles at the same rate to test the longevity of the electrodes?
5. The authors are encouraged to compare the performance of their electrode (both energy and power density) to other supercapatteries available in their discussion.
Comments on the Quality of English Language
Minor English editing is needed for improvement and some typos need to be corrected too. For example, in Line 69 “surface” should be “sulfur”.
Author Response
Comment-1: In the Experimental Section, the author mentioned XRD, TEM and EDS were performed to characterize the electrodes but I did not see them in the results. Can the authors provide the data and discussion, since these data are important to demonstrate the hierarchical structure?
Answer: Thank you for your correction. We have provided the details of XRD, TEM and EDS of NiS2 in our earlier published article and the same is cited in the Experimental Section as Ref-21. A detailed explanation may end up in plagiarism hence not provided here.
Comment-2: Have the authors done SEM (or maybe XRD and TEM) on the NiS2@PEDOT:PSS made with different PEDOT:PSS concentration? I think the authors can elaborate on this as the data could explain why the authors saw reduced performance in the electrodes made with high PEDOT:PSS concentration.
Answer: Thank you for your suggestion. We have limited sources to carry out the TEM characterization as it is very expensive. Hence, we have performed the FESEM analysis of the best-performing electrode only.
Comment-3: The authors need to provide more references in support of their discussion. For examples, all the equations used in the manuscript, and the explanation of total charge distribution in NPS1 electrode, etc.
Answer: Thank you for your comment. As per your comment, we have incorporated more references in the revised manuscript detailing the same.
Comment-4: (a) In Figure 3b, what exactly contributed to the increased anodic current in NPS1 material? (b) Have the authors scanned the electrodes with multiple cycles at the same rate to test the longevity of the electrodes?
Answer: Thank you for your comment. (a) There are many variables play a role in determining the electrochemical performance in a SC electrode. In the present study, since the NiS2 exhibits battery-type charge storage, the open ionic channels play an important role in the specific capacity and direct evidence for the same can’t be attained from any of the physical characterizations. (b) Yes, we have scanned the electrodes with multiple cycles to test the longevity.
Comment-5: The authors are encouraged to compare the performance of their electrode (both energy and power density) to other supercapatteries available in their discussion.
Answer: Thank you for your comment. As per your comment, we have provided a comparative analysis on performance of electrode in terms of energy and power density in our revised manuscript as Table 1 (Page No.14).
Comment-6: Comments on the Quality of English Language: Minor English editing is needed for improvement and some typos need to be corrected too. For example, in Line 69 “surface” should be “sulfur”.
Answer: Thank you for your valuable comment. As per your comment, we have improved the quality of English language in our revised manuscript by removing typo errors.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors performed all recommended chances and now I am able to recommend this paper to be accepted.
Reviewer 2 Report
Comments and Suggestions for AuthorsNow the paper looks much better. I accept the new version of the paper.
