Round 1

Reviewer 1 Report

Please check the attached file of the comments.

Comments for author File: Comments.pdf

Author Response

Respond to Reviewer 1 Comments

 

Dear the reviewer,

We reported a study on the use of biomass, namely water hyacinth as a porous carbon material made into composites for cathode applications in lithium-sulfur batteries. We found high sulfur content in water hyacinth activated charcoal composites carbonized at 600 ^oC with ZnCl₂ activator in a ratio of 1:3, which indicates that porous carbon from biomass is also able to compete with other popular types. Porous carbon materials with large surface area and high electrical conductivity have been used for cathode composites and have shown good performance of lithium sulfur batteries. This research is important to be reported as one of the results of research to obtain environmentally friendly batteries derived from abundant biomass that have not been used optimally. Therefore, we hope that our paper can be accepted for publication in Sustainability.

We would like to thank for some comments and suggestions from reviewers to our manuscript. Below is our responds to reviewer’s comments and suggestions.

=======================================================================

Reviewer 1: This paper proposes the application of porous carbon made from water hyacinth as a composite cathode for lithium-sulphur batteries. The electrical conductivity of the composite is tested and investigated, and the initial discharge capacity of the battery for porous carbon with sulphur content is also measured. The concept is interesting, and the methodology is well presented, but the paper needs some major revisions.

Respond: Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript.

We have greatly revised this manuscript according to the reviewer's direction. The improvement we have made is to take a composite ratio value of 1:2.5. This has many consequences for the discussion of the results of the XRD, SEM, BET, TGA and battery test characterizations. This is done so that the results of the application of porous carbon on lithium sulfur batteries are slightly better than before, although the initial discharge capacity is still low (less than 500 mAh/g). We expect a good response from reviewers.

 

Reviewer 1:

Point 1. The novelty/originality shall be further justified by highlighting that the manuscript contains sufficient contributions to the new body of knowledge. The knowledge gap needs to be clearly addressed in the Introduction.

 

Respond: Authors would like to thank for valuable comments and suggestions.

 

This manuscript is a continuation of a previous study published in the sustainability journal in 2021. The novelty in this research is the utilization of water hyacinth waste in the form of porous carbon for lithium sulfur battery cathode applications. Porous carbon was chosen as the matrix for sulfur because porous carbon has good properties although it is not as good as other carbon materials such as graphene.

Reviewer 1:

Point 2. In Figure 1, the intense peak should be highlighted for both left and right figures. Also, the figures have so many peaks, which seems like the material is not pure enough; please explain.

 Respond: Authors would like to thank for valuable comments and suggestions

 

We acknowledge that it is difficult to obtain pure carbonaceous materials so that the diffraction pattern gives rise to many peaks. The purity level of the carbon material is about 60% based on SEM-EDS data. In the article that we have corrected, the XRD pattern of the carbon material is no longer displayed. The XRD pattern only displays composites and pure sulfur. We hope that there will be a good response to these improvements.

 

Reviewer 1:

Point 3. Can you add some SEM or TEM analysis for the morphological characterization to further show the composite surface with a more informative explanation?

Respond: Authors would like to thank for valuable comments and suggestions

We have replaced the SEM images for the porous carbon samples and their composites with higher resolution images. Figure 2 (a and b) is the SEM image we referred to in the previous article (ref 29). Then, we have added information related to SEM analysis.

 

Reviewer 1:

Point 4. For reference 26, please add more details of this reference. The cited reference should have the publication date and page number, etc.

 Respond: Authors would like to thank for valuable comments and suggestions 

Reference 26 has changed to ref No. 31 and the journal names, volume and page have been corrected.

 

Reviewer 1:

Point 5. The format of the manuscript should be carefully revised, for example: 1) Each paragraph should have the same first-line indent. 2) Figure 3 was mentioned as Figure (a) and (b) in the paragraph, but the title of Figure 3 is written with left and right. 3) All the subtitles should follow the style provided by the template of the journal

 

Respond: Authors would like to thank for valuable comments and suggestions 

• We have corrected the indentation of the first line of each paragraph.
• Figure 3 has been clarified by providing information (a) and (b) on each image
• All subtitles have been fixed by following the journal template.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the attachment.

Comments for author File: Comments.pdf

Author Response

Respond to Reviewer 2 Comments

 

Dear the reviewer,

 

We reported a study on the use of biomass, namely water hyacinth as a porous carbon material made into composites for cathode applications in lithium-sulfur batteries. We found high sulfur content in water hyacinth activated charcoal composites carbonized at 600 oC with ZnCl2 activator in a ratio of 1:3, which indicates that porous carbon from biomass is also able to compete with other popular types. Porous carbon materials with large surface area and high electrical conductivity have been used for cathode composites and have shown good performance of lithium sulfur batteries. This research is important to be reported as one of the results of research to obtain environmentally friendly batteries derived from abundant biomass that have not been used optimally. Therefore, we hope that our paper can be accepted for publication in Sustainability.

We would like to thank for some comments and suggestions from reviewers to our manuscript. Below is our responds to reviewer’s comments and suggestions.

 

 

Reviewer 2:

Summary

1. This work synthesized porous carbon from water hyacinth and inserted Sulfur into it. The composite materials was used as cathode for Li-S battery testing.
2. General comments Overall very poor quality paper. The introduction is too short and incomplete. The methods description is too simple, hindering reproducibility. There is no characterization method description at all. The materials characterization results have very bad quality. The batteries testing showed that both samples had very bad performance. The author needs a major revision on it.
3. Improvements that you could suggest on the paper

Respond: Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript.

We have improved this manuscript by completing the introduction. We have also completed experimental methods and characterization methods. We have made major changes to improve the quality of this manuscript.

 

Major Improvement:

Reviewer 2:

Point 1. Page 1, Abstract. In the abstract, the author is suggested to briefly mention why porous carbon derived from water hyacinth is used. What is the advantage of this porous carbon compared to other carbon sources.

 Respond: Authors would like to thank for valuable comments and suggestions.

 

We have added in the abstract the reasons for the porous carbon of water hyacinth and its advantages over others.

 

Reviewer 2:

Point 2. Page 1, line 48. If the water hyacinth has so much impurities, how to filter them? How to make sure the impurities don’t affect battery.

 

Respond: Authors would like to thank for valuable comments and suggestions

 

We have strived to obtain high purity porous carbon. One way is to do the heating process (calcination) at a temperature of 800 ^oC under the atmosphere of Ar. From the results of SEM-EDS the level of carbon purity is only 60%. The level of purity that is less will certainly affect the performance of the battery, especially the value of the electrical conductivity of the matrix. In our understanding, battery performance is generally determined by the sulfur loadingt of the cathode, so in this study we tried to increase the sulfur loading by coating the cathode slurry on aluminum foil with a thickness of 200 micrometers.

 

Reviewer 2:

Point 3. Page 2, line 52-58. Overall, the introduction part is too short. Especially the introduction to Li-S batteries is superficial, just two sentences. The author should summarize the state of the world research on Li-S cathode. What are current bottlenecks. What previous works have been done and how they can improved. Finally, why water hyacinth is selected in this work

 

Respond: Authors would like to thank for valuable comments and suggestions

We've added a discussion of Li-S batteries to the introduction. We have also added an argument, why water hyacinth was chosen in this work.

 

Reviewer 2:

Point 4. Page 2, line 76. Different weight ratio samples should have different C rates. Why is the 1C defined as fixed 1675 mA/g directly?

 

Respond: Authors would like to thank for valuable comments and suggestions

Different sulfur content will affect the initial discharging capacity. In this study, higher sulfur content resulted in higher initial discharging capacity. The scan rate used for discharge testing is generally 1C which corresponds to the theoretical specific capacity of 1675 mAh/g.

 

Reviewer 2:

Point 5. Page 2, methods. There is no description on how characterizations are performed? Very weird

 Respond: Authors would like to thank for valuable comments and suggestions

We have added and revised about methods and descriptions for all the characterizations that have been carried out.

 

Reviewer 2:

Point 6. Page 3, line 80-95. The author should mark the peaks in the Figure. The XRD graph is too noisy. It is hard to tell which peak the author refers to. By the way, besides the (002) (100) planes, there are so many others peaks in the graphs. What are they? o The author mentioned “graphite”. Is the goal to transfer the porous C into graphite?.

 

Respond: Authors would like to thank for valuable comments and suggestions

On the XRD graph there are still many crystal peaks which indicate that the porous carbon sample does not have a high level of purity. Supposedly, the XRD graph only shows two peaks, namely at angles of 2theta 26 and 43. In the manuscript that we have corrected, we do not include XRD pattern images for porous carbon, we only include sulfur and composite XRD pattern images. We hope to get a good response from reviewers.

In the XRD graph analysis, the peak angles 26 and 43 are used as a reference for the quality of the carbon sample. Angles 26 and 43 are typical angles of graphite. The discussion about graphite has been removed from the revised manuscript.

 

 

Reviewer 2:

Point 7. Page 3, line 88. “The presence of peak (222) in the WHPC/S composite indicates that sulfur has entered the WHPC.” No sure what is the meaning of “entered”.

 

Respond: Authors would like to thank for valuable comments and suggestions

What this means is that sulfur has been impregnated into the porous carbon pores

 

Reviewer 2:

Point 8. Page 3, line 92. SEM can only show a very local region. It can’t support 1:2.5 distribute more evenly. The two images have very bad quality and low resolution. EDS mapping tests should be performed to see the element distribution, not by eyes

 

Respond: Authors would like to thank for valuable comments and suggestions

We have added SEM analysis of porous carbon and its composites

 

 

Reviewer 2:

Point 9. Page 4, line 120. It could just be the temperature increase rate is too fast and weight of pure sulfur is too much. There is no evidence of “weak bond”

 

Respond: Authors would like to thank for valuable comments and suggestions

We have revised the discussion of the weak bond between C and S in the revised manuscript.

 

Reviewer 2:

Point 10. Page 4, line 130. It is very confusing what thickness doubles, but Sulfur loading doesn’t. How does the author determine the S loading?

 

Respond: Authors would like to thank for valuable comments and suggestions

Sulfur loading is determined based on the thickness of the cathode slurry layer on the Al foil. Sulfur loading is calculated according to the coin cell area of ​​the battery.

 

Reviewer 2:

Point 11. Page 5, line 134-141. It is meaningless to see the so-called highest capacity. It is well known that initial cycle capacity has a lot of activation reaction. Only when capacity curve is stable, the capacity can be treated as reversible

 

Respond: Authors would like to thank for valuable comments and suggestions

We have revised the discussion regarding initial discharging capacity.

 

Reviewer 2:

Point 12. Page 5, line 159. No idea how the author conclude two batteries had good performance. Basically, from Figure 5, it can only tell both batteries had very bad performance. For battery (a), the initial CE and capacity oscillate dramatically, indicating the electrochemical system is unstable. This usually comes from bad fabrication process. For battery (b), although the curve looks smooth, but the CE overall is pretty low

 

Respond: Authors would like to thank for valuable comments and suggestions

We are aware that the battery that has been made has a poor performance. This is indicated by a low initial discharge capacity (less than 500 mAh/g) and a low coulombic efficiency value (70%). However, we think that the battery manufacture in the early stages has been a success as indicated by the charging and discharging process up to the 50th cycle.

 

 

Reviewer 2:

Point 13. Page 6, Figure 6. It is usual to perform rate testing from low rate to high rate, 0.1C to 1.0C. No idea why the author did the opposite

 

Respond: Authors would like to thank for valuable comments and suggestions

We have improved the cyclability test and discussion starting with a low scant rate of 0.1 C.

 

 

Reviewer 2:

Point 14. Page 6, line 169. “The smaller the rate of charge given, the value of the discharge capacity increases.” This is just due to internal overpotential, not real capacity change. The author is suggested to revisit some basics of electrochemistry.

 

Respond: Authors would like to thank for valuable comments and suggestions

Based on the measurement of cyclicality, the smaller scan rate, the greater the value of the discharging capacity. We've improved the discussion on cyclability.

 

Reviewer 2:

Point 15.Throughout the whole results and discussion, the author didn’t explain why 1:3.5 seems to be better than 1:2.5. They just read the graph, without any in-depth discussion.

 

Respond: Authors would like to thank for valuable comments and suggestions

 

We have revised the discussion in this manuscript to only discuss composite samples with a weight ratio of 1:2.5 because the composite applied to the battery is a composite with a weight ratio of 1:2.5. We hope to get a good response from reviewers.

 

 

Minor Improvement:

Reviewer 2:

Point 16. Page 2, line 54. The word “poor performance” here is too general.

 

Respond: Authors would like to thank for valuable comments and suggestions

We've revised the word "poor performance"

 

Reviewer 2:

Point 17. Page 2, line 63. What is the meaning of “variations” of 1:2.5 and 1:3.5. Is it weight ratio?

 

Respond: Authors would like to thank for valuable comments and suggestions

We have revised by explaining that the ratio in question is the weight ratio.

 

Reviewer 2:

Point 18. Page 3, line 81. Can’t understand what is “a low degree of gravity”

 

Respond: Authors would like to thank for valuable comments and suggestions

We have revised the discussion about a low ddegree of gravity. What is meant is the degree of graphitization.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author addressed all the comments and revised the manuscript. The revised manuscript is recommended to be published in this journal.

Author Response

Respond to Reviewer 1 Comments

 

Dear the reviewer,

We reported a study on the use of biomass, namely water hyacinth as a porous carbon material made into composites for cathode applications in lithium-sulfur batteries. We found high sulfur content in water hyacinth activated charcoal composites carbonized at 600 ^oC with ZnCl₂ activator in a ratio of 1:3, which indicates that porous carbon from biomass is also able to compete with other popular types. Porous carbon materials with large surface area and high electrical conductivity have been used for cathode composites and have shown good performance of lithium sulfur batteries. This research is important to be reported as one of the results of research to obtain environmentally friendly batteries derived from abundant biomass that have not been used optimally. Therefore, we hope that our paper can be accepted for publication in Sustainability.

We would like to thank for some comments and suggestions from reviewers to our manuscript. Below is our responds to reviewer’s comments and suggestions.

=======================================================================

Reviewer 1: This paper proposes the application of porous carbon made from water hyacinth as a composite cathode for lithium-sulphur batteries. The electrical conductivity of the composite is tested and investigated, and the initial discharge capacity of the battery for porous carbon with sulphur content is also measured. The concept is interesting, and the methodology is well presented, but the paper needs some major revisions.

Respond: Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript.

We have greatly revised this manuscript according to the reviewer's direction. The improvement we have made is to take a composite ratio value of 1:2.5. This has many consequences for the discussion of the results of the XRD, SEM, BET, TGA and battery test characterizations. This is done so that the results of the application of porous carbon on lithium sulfur batteries are slightly better than before, although the initial discharge capacity is still low (less than 500 mAh/g). We expect a good response from reviewers.

 

Reviewer 1:

Point 1. The novelty/originality shall be further justified by highlighting that the manuscript contains sufficient contributions to the new body of knowledge. The knowledge gap needs to be clearly addressed in the Introduction.

 

Respond:.

 

This manuscript is a continuation of a previous study published in the sustainability journal in 2021. The novelty in this research is the utilization of water hyacinth waste in the form of porous carbon for lithium sulfur battery cathode applications. Porous carbon was chosen as the matrix for sulfur because porous carbon has good properties although it is not as good as other carbon materials such as graphene.

Reviewer 1:

Point 2. In Figure 1, the intense peak should be highlighted for both left and right figures. Also, the figures have so many peaks, which seems like the material is not pure enough; please explain.

 Respond:

 

We acknowledge that it is difficult to obtain pure carbonaceous materials so that the diffraction pattern gives rise to many peaks. The purity level of the carbon material is about 60% based on SEM-EDS data. In the article that we have corrected, the XRD pattern of the carbon material is no longer displayed. The XRD pattern only displays composites and pure sulfur. We hope that there will be a good response to these improvements.

 

Reviewer 1:

Point 3. Can you add some SEM or TEM analysis for the morphological characterization to further show the composite surface with a more informative explanation?

Respond:

We have replaced the SEM images for the porous carbon samples and their composites with higher resolution images. Figure 2 (a and b) is the SEM image we referred to in the previous article (ref 29). Then, we have added information related to SEM analysis.

 

Reviewer 1:

Point 4. For reference 26, please add more details of this reference. The cited reference should have the publication date and page number, etc.

 Respond:  

Reference 26 has changed to ref No. 31 and the journal names, volume and page have been corrected.

 

Reviewer 1:

Point 5. The format of the manuscript should be carefully revised, for example: 1) Each paragraph should have the same first-line indent. 2) Figure 3 was mentioned as Figure (a) and (b) in the paragraph, but the title of Figure 3 is written with left and right. 3) All the subtitles should follow the style provided by the template of the journal

 

Respond:

• We have corrected the indentation of the first line of each paragraph.
• Figure 3 has been clarified by providing information (a) and (b) on each image
• All subtitles have been fixed by following the journal template.

 

Thanks….

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the attachment.

Comments for author File: Comments.pdf

Author Response

Respond to Reviewer 2 Comments Round 2

 

Summary

 

1. This work synthesized porous carbon from water hyacinth and inserted Sulfur into it. The composite materials was used as cathode for Li-S battery testing.

 

2. General comments Overall very poor quality paper. The introduction is too short and The methods description is too simple, hindering reproducibility. There is no characterization method description at all. The materials characterization results have very bad quality. The batteries testing showed that both samples had very bad performance. The author needs a major revision on it.

 

3. Improvements that you could suggest on the paper

 

Respond: Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript.

 

We have improved this manuscript by completing the introduction. We have also completed experimental methods and characterization methods. We have made major changes to improve the quality of this manuscript.

 

Major Improvement:

 

Reviewer 2:

 

Point 1. Page 1, Abstract. In the abstract, the author is suggested to briefly mention why porous carbon derived from water hyacinth is used. What is the advantage of this porous carbon compared to other carbon sources.

 

Respond:

 

We have added in the abstract the reasons for the porous carbon of water hyacinth and its advantages over others.

 

Re: The abstract looks better. More advantage/disadvantages comparison to other carbon sources are also encouraged in introduction part.

 

Respond: We added some explanations about advantage and disadvantages of carbon source in present manuscript and other sources in the introduction.

 

Reviewer 2:

 

Point 2. Page 1, line 48. If the water hyacinth has so much impurities, how to filter them? How to make sure the impurities don’t affect battery.

 

Respond:

 

We have strived to obtain high purity porous carbon. One way is to do the heating process (calcination) at a temperature of 800 ^oC under the atmosphere of Ar. From the results of SEM- EDS the level of carbon purity is only 60%. The level of purity that is less will certainly affect the performance of the battery, especially the value of the electrical conductivity of the matrix. In our understanding, battery performance is generally determined by the sulfur loading of the cathode, so in this study we tried to increase the sulfur loading by coating the cathode slurry on aluminum foil with a thickness of 200 micrometers.

 

Re: “battery performance is generally determined by the sulfur loading”. The reviewer can’t agree with the author’s comment here. Without good conductivity, high sulfur loading will have very fast capacity drop.

 

Respond: Thank you for your correction of our understanding. In this study, we are concerned about the conductivity of porous carbon. We agree that the electrochemical performance of the battery depends also on the conductivity of the matrix. The increase in sulfur content at the cathode aims to increase the amount of sulfur involved in the electrochemical process. 

 

Reviewer 2:

 

Point 3. Page 2, line 52-58. Overall, the introduction part is too short. Especially the introduction to Li-S batteries is superficial, just two sentences. The author should summarize the state of the world research on Li-S cathode. What are current bottlenecks. What previous works have been done and how they can improved. Finally, why water hyacinth is selected in this work

 

Respond:

We've added a discussion of Li-S batteries to the introduction. We have also added an argument, why water hyacinth was chosen in this work.

 

Re: Now it looks better. Thanks.

 

Respond: Thanks.

 

Reviewer 2:

 

Point 4. Page 2, line 76. Different weight ratio samples should have different C rates. Why is the 1C defined as fixed 1675 mA/g directly?

 

Respond:

Different sulfur content will affect the initial discharging capacity. In this study, higher sulfur content resulted in higher initial discharging capacity. The scan rate used for discharge testing is generally 1C which corresponds to the theoretical specific capacity of 1675 mAh/g.

 

Re: Thanks.

    Respond: Thank you for your correction of our understanding.

 

Reviewer 2:

Point 5. Page 2, methods. There is no description on how characterizations are performed? Very weird

 

Respond:

We have added and revised about methods and descriptions for all the characterizations that have been carried out.

 

Re: Thanks.

    Respond: Thank you for your correction of our understanding.

 

Reviewer 2:

 

Point 6. Page 3, line 80-95. The author should mark the peaks in the Figure. The XRD graph is too noisy. It is hard to tell which peak the author refers to. By the way, besides the (002) (100) planes, there are so many others peaks in the graphs. What are they? o The author mentioned “graphite”. Is the goal to transfer the porous C into graphite?.

 

Respond:

 

On the XRD graph there are still many crystal peaks which indicate that the porous carbon sample does not have a high level of purity. Supposedly, the XRD graph only shows two peaks, namely at angles of 2theta 26 and 43. In the manuscript that we have corrected, we do not include XRD pattern images for porous carbon, we only include sulfur and composite XRD pattern images. We hope to get a good response from reviewers.

 

In the XRD graph analysis, the peak angles 26 and 43 are used as a reference for the quality of the carbon sample. Angles 26 and 43 are typical angles of graphite. The discussion about graphite has been removed from the revised manuscript.

 

Re: The reviewer didn’t imply the original XRD for WHPC should be removed. In fact, as a paper studying this materials, it is necessary to include WHPC only XRD pattern. Although there are many noise peaks in the original Figure 1(a). But overall, the peak is sharp, indicating good crystallinity. The author should make most of their experiment results and provide meaningful interpretation.

 

The Sulfur XRD alone is not useful. It is widely known. And its peaks dominate WHPC.

 

Respond: Thanks for your correction of the WHPC XRD pattern curve from being deleted.We have re-entered the XRD pattern curve of the WHPC in the manuscript (Fig. 1a) and have provided an explanation of the noisy crystal peaks. We have also included your correction of the XRD curve of sulfur. Figure 2a shows the composite XRD pattern with two variations of the weight ratio. However, for the next analysis, we only discuss composite samples with a weight variation of 1:2.5.

 

Reviewer 2:

 

Point 7. Page 3, line 88. “The presence of peak (222) in the WHPC/S composite indicates that sulfur has entered the WHPC.” No sure what is the meaning of “entered”.

 

 

 

Respond: Authors would like to thank for valuable comments and suggestions. The meaning of “entered” in page 3 is that sulfur has been impregnated into the porous carbon pores

 

Re: It can also prove sulfur is on the surface.

 

 Respond: Thanks

 

Reviewer 2:

 

Point 8. Page 3, line 92. SEM can only show a very local region. It can’t support 1:2.5 distribute more evenly. The two images have very bad quality and low resolution. EDS mapping tests should be performed to see the element distribution, not by eyes

 

Respond:

We have added SEM analysis of porous carbon and its composites

 

Re: Although the updated images have higher quality, the reviewer still thinks only EDS mapping can show “the sulfur particles get well diffused into the pores” line 152.

 

Respond: Thank you for your correction. To support the explanation of the noisy WHPC and WHPC/S sample XRD patterns, we present EDS mapping images of WHPC and WHPC/S. In addition, the EDS mapping image can also explain the surface morphology of the sulfur in the composite. In addition, we also add a table about the content of elements in the WHPC sample to prove that the sample has a purity level of about 66%.

 

Reviewer 2:

 

Point 9. Page 4, line 120. It could just be the temperature increase rate is too fast and weight of pure sulfur is too much. There is no evidence of “weak bond”

 

Respond:

We have revised the discussion of the weak bond between C and S in the revised manuscript. Re: Thanks.

Respond: Authors would like to thank for valuable comments and suggestions

Reviewer 2:

 

Point 10. Page 4, line 130. It is very confusing what thickness doubles, but Sulfur loading doesn’t. How does the author determine the S loading?

 

Respond:

Sulfur loading is determined based on the thickness of the cathode slurry layer on the Al foil. Sulfur loading is calculated according to the coin cell area of the battery.

 

Re: No sure how the weight can be determined by the thickness. To more precisely measure weight, pristine WHPC should be first weighted. Then coating sulfur. Finally measure final weight and take difference.

 

Respond; Thanks you for your correction.

The procedure we use to measure the sulfur loading at the cathode is as follows, we first weigh the empty al foil whose area corresponds to the area of ​​​​the coin cell battery. Next, we coated the cathode slurry with a doctor blade at a thickness of 200 micrometers. Weigh the coated Al foil. The difference in weight between the blank al foil and the coated al foil was determined as the sulfur loading in mg/cm2.

 

 

Reviewer 2:

 

Point 11. Page 5, line 134-141. It is meaningless to see the so-called highest capacity. It is well known that initial cycle capacity has a lot of activation reaction. Only when capacity curve is stable, the capacity can be treated as reversible

 

Respond: We have revised the discussion regarding initial discharging capacity.

 

Re: Thanks.

 

  Respond: Authors would like to thank for valuable comments and suggestions

 

Reviewer 2:

 

Point 12. Page 5, line 159. No idea how the author conclude two batteries had good performance. Basically, from Figure 5, it can only tell both batteries had very bad performance. For battery (a), the initial CE and capacity oscillate dramatically, indicating the electrochemical system is unstable. This usually comes from bad fabrication process. For battery (b), although    the curve looks smooth, but the CE overall is pretty low

 

Respond:

We are aware that the battery that has been made has a poor performance. This is indicated by a low initial discharge capacity (less than 500 mAh/g) and a low coulombic efficiency value (70%). However, we think that the battery manufacture in the early stages has been a success as indicated by the charging and discharging process up to the 50th cycle.

 

Re: Given the author admitted poor performance, the reviewer doesn’t have further comments.

 

Reviewer 2:

 

  Respond: Authors would like to thank for valuable comments and suggestions

 

Point 13. Page 6, Figure 6. It is usual to perform rate testing from low rate to high rate, 0.1C to 1.0C. No idea why the author did the opposite

 

Respond:

We have improved the cyclability test and discussion starting with a low scant rate of 0.1 C. Re: Thanks.

Respond: Authors would like to thank for valuable comments and suggestions

Reviewer 2:

 

Point 14. Page 6, line 169. “The smaller the rate of charge given, the value of the discharge capacity increases.” This is just due to internal overpotential, not real capacity change. The author is suggested to revisit some basics of electrochemistry.

 

 

Respond:

Based on the measurement of cyclicality, the smaller scan rate, the greater the value of the discharging capacity. We've improved the discussion on cyclability.

 

Re: No much new in-depth discussion can be seen.

 

Respond: Thanks for your comment.

We have attempted to add to the explanation of battery cyclability by adding a specific capacity value for each scan-rate. When charging the battery is restored to the initial scan rate, the battery capacity value is still obtained with a lower value.

 

Reviewer 2:

 

Point 15.Throughout the whole results and discussion, the author didn’t explain why 1:3.5 seems to be better than 1:2.5. They just read the graph, without any in-depth discussion.

 

Respond:

 

We have revised the discussion in this manuscript to only discuss composite samples with a weight ratio of 1:2.5 because the composite applied to the battery is a composite with a weight ratio of 1:2.5. We hope to get a good response from reviewers.

 

Re: The author shouldn’t avoid question, but answer question……

 

 

Respond; thanks for your comment.The explanation of the WHPC/S composite ratio is as follows. For a WHPC/S weight ratio of 1:3.5, the sulfur content in the composite was about 80 wt%, a WHPC/S ratio of 1:2.5 was obtained about 60%. However, a higher sulfur content in the composite does not necessarily result in a battery with better performance. We refer to reference 30. In this research we take a composite with a ratio of 1:2.5 as the cathode of this battery. Based on the tests, the battery performance with a ratio of 1:2.5 is better than the ratio of 1:3.5.

 

Minor Improvement:

 

Reviewer 2:

 

Point 16. Page 2, line 54. The word “poor performance” here is too general.

 

Respond:

 

We've revised the word "poor performance"

 

Reviewer 2:

 

Point 17. Page 2, line 63. What is the meaning of “variations” of 1:2.5 and 1:3.5. Is it weight ratio?

 

Respond:

 

We have revised by explaining that the ratio in question is the weight ratio.

 

Reviewer 2:

 

Point 18. Page 3, line 81. Can’t understand what is “a low degree of gravity”

 

Respond:

We have revised the discussion about a low degree of gravity. What is meant is the degree of graphitization.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Hi Author,

1. Are the EDS images (Figure. 2 c-h) real?

(1) If you previously took the EDS, why didn't you provide it before?

(2) If you previously didn't take the image, how is it possible to find exactly the same sample/same orientation to take the EDS images again?

(3) Why Carbon (red) signal is not on the WHPC flake, but on the background. (Sub figure (d))
(4) Obviously, (d)+(e)+(f) overlap is NOT equal to (c). There are weird clustered green and blue dots in (c). Looks like they are manually drawn separately.

(5) No idea what are (g)(h)? Are they from sample in (b)?

(6)In table 1, given % weight of C and O are 66.33 and 9.48. As a high school knowledge, Carbon atomic mass is 12, Oxygen's is 16. So we can calculate molar ratio is (66.33/12)/(9.48/16)=9.32.
BUT, the author gives 80.32/9.18 = 8.75. ???

Author Response

Respond to Reviewer 2 Comments Round 3

 

Respond: Authors would like to thank you for your valuable comments and suggestions to increase the quality of our manuscript.

1. Are the EDS images (Figure. 2 c-h) real?

Respond;

Yes, all the EDS images are real images. We have revised Figure 2 to make it easier for readers to understand. Figure 2(b) is the EDS mapping of WHPC. For Figure 2(c) – 2(f), the EDS mapping is concentrated for Carbon (black) (Fig. 2(c)), Zn (blue) (Fig. 2(d)), Cl (brown) (Fig. 2(e)) and O (purplish) (Fig. 2(f)). For Fig. 2(c), we have revised the caption for the C element to be black, while the red color is the background.

 

• If you previously took the EDS, why didn't you provide it before?

Respond;Regarding the EDS data, in the first manuscript, we think the SEM images are sufficient to explain the surface morphology of the WHPC. We followed the suggestion from the reviewer to display the EDS map as well to support other data, such as XRD data, so that the information is more comprehensive.

• If you previously didn't take the image, how is it possible to find exactly the same sample/same orientation to take the EDS images again?

Respond;Actually, we already have the EDS mapping data from which we drafted the manuscript. So, we only need to display the maps after getting suggestions from the reviewers.  

• Why Carbon (red) signal is not on the WHPC flake, but on the background. (Sub figure (d))

Respond:Thank you for your valuable comments and corrections. We corrected the explanation of the color in Figures 2 (b) and 2 (c). The red color should be the background. The color of the WHPC flake is gray.
(4) Obviously, (d)+(e)+(f) overlap is NOT equal to (c). There are weird clustered green and blue dots in (c). Looks like they are manually drawn separately. Respond; All EDS map images shown in Figure 2 were obtained from SEM-EDS measurements. We do not manually draw the images. The cluster of blue dots seen in Figure 2(b) is defined as the cluster of Zn elements that we show in Figure 2(d). While the green color cluster is not shown in Figure 2. We only show clusters of elements that have dominant content (carbon (66.33 %wt), O (9.48%wt), Cl (8.67 %wt), and Zn (4.29 %wt)). We show the cluster map of Zn and Cl because we also use these elements as activators. 

• No idea what are (g)(h)? Are they from the sample in (b)?

Respond;We have revised Figure 2 to make it easier for readers to understand. Figure 2(g) is the SEM of WHPC/S, Figure 2(h) is the EDS Map of WHPC/S, Figure 2(i) is the EDS Map for C and Figure 2 (j) is the EDS Map of WHPC/S for S. Both images are sourced from the SEM image of WHPC/S that we show in Figure 2 (g). 

 (6)In table 1, given % weight of C and O are 66.33 and 9.48. As a high school knowledge, Carbon atomic mass is 12, Oxygen's is 16. So we can calculate molar ratio is (66.33/12)/(9.48/16)=9.32.
BUT, the author gives 80.32/9.18 = 8.75. ???

Respond;

Thank you for your comments and correction. We re-calculated the average of weight % and atomic % from 8 measuring points to get the appropriate values for weight % and atomic % of all elements in WHPC. We revised the content of Table 1.

 

 

Author Response File: Author Response.pdf