High Sulfur Content of Mesoporous Activated Carbon Composite Derived from Water Hyacinth

Round 1

Reviewer 1 Report

Comments on manuscript entitled: High Sulfur Content of Mesoporous Activated Carbon Compo-2 site Derived from Water Hyacinth

Journal: MDPI / Sustainability

 

 

In this manuscript, activated carbon from water hyacinth with high surface area, large pore volume, high conductivity, and high sulfur content was made for the application of lithium-sulfur battery cathode composites. For this case, activated carbon was made from water hyacinth which was carbonized at a temperature of 600 oC 16 with a ZnCl2 activator. The N2 desorption-adsorption test results obtained a surface area of 642.39 17 m2g-1, a total pore volume of 0.714 cm3g-1, and a pore diameter of 2.22 nm.

After a careful peer-reviewing process, I must inform you that, the subject of this paper is interesting. I believe that the paper contains relevant information for the scientific community, especially in the field of advanced lithium-sulfur batteries (LSB). I believe that the results are informative but must be well organized and improved in the next revision(s). Therefore, there are some questions about this submission and some revisions are necessary for this work. The major/minor issues are indicated as follows:

 

1. The abstract is not well written but some details of the experimental processes especially on the production of activated carbon, preparation of activated carbon-sulfur composite as well as conductivity measurements were missed in the abstract. Please revise this section.

 

2. The new findings related to this work should be stated in the introduction clearly.

 

3. The state of the art needs to be described more in the introduction. This information could help to show the lack of knowledge in the author's field of research.

 

4. Authors must show which questions/problems have been answered in this work. In this case, the correct and detailed definition of the volumetric 43 changes during the charge and discharge process must be provided in this manuscript.

 

5. Please provide the manufacturer/model/code and also the manufacturer country of the raw materials as well as all testing equipment used for evaluations.

 

6. It is beneficial to provide more information about Conductivity measurement in section 2.3.

 

7. A step-by-step flowchart is beneficial to provide useful information in experimental processes.

 

8. Detailed comments are required for this statement: “AC samples exhibited a pore distribution at above 2 nm, corresponding to high amounts of mesopores. 128 The adsorption behavior on mesoporous is in the form of multilayer adsorption followed by pore condensation which describes the vapor to liquid phase transition, which is determined by the interaction of the sample with the gas and also by the interactions be-131 tween the adsorbate molecules in the condensed state [28].”.

 

9. In this manuscript, results are well presented, but discussion on the obtained results must be completely provided in this manuscript. As can be seen, a “comprehensive” and “comparative” discussion (e.g, for experimental data in Conductivity measurement and XRD phase detection) are missed in this work. This should be provided as well.

 

10. Please provide ICDD reference codes for each detected phase in XRD tests.

 

11. There is no description of the future plans for research in the first part of the “Conclusions” section. This should be completed in section 6.

 

12. Recently published references are beneficial for this work. Please check and use new references focused on your work.

 

13. Also, please double-check and revise the reference list according to the journal requirements.

 

14. The English of this manuscript needs to be improved. Please check and revise the English language of the main text of the manuscript and also figure/table captions.

Author Response

Respond to Reviewer 1 Comments

 

Dear the reviewer,

We reported a study on the use of biomass, namely water hyacinth as an active carbon material made into composites for cathode applications in lithium-sulfur batteries. We found that the high sulfur content in the composite activated charcoal from water hyacinth which was carbonized at a temperature of 600 ^oC with ZnCl₂ activator with ratio 1:3, which indicates that activated carbon from biomass is also able to compete with other popular types of carbon materials with large surface area and pore volume and high electrical conductivity. This study is important to be reported as one of the results of research to obtain environmentally friendly battery materials derived from abundant and not optimally utilized biomass. Therefore, we hope an acceptance of our paper for publishing in the 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: In this manuscript, activated carbon from water hyacinth with high surface area, large pore volume, high conductivity, and high sulfur content was made for the application of lithium-sulfur battery cathode composites. For this case, activated carbon was made from water hyacinth which was carbonized at a temperature of 600 ^oC 16 with a ZnCl2 activator. The N2 desorption-adsorption test results obtained a surface area of 642.39 17 m2g-1, a total pore volume of 0.714 cm3g-1, and a pore diameter of 2.22 nm.

After a careful peer-reviewing process, I must inform you that, the subject of this paper is interesting. I believe that the paper contains relevant information for the scientific community, especially in the field of advanced lithium-sulfur batteries (LSB). I believe that the results are informative but must be well organized and improved in the next revision(s). Therefore, there are some questions about this submission and some revisions are necessary for this work.

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

Reviewer 1: The major/minor issues are indicated as follows:

Point 1. The abstract is not well written but some details of the experimental processes especially on the production of activated carbon, preparation of activated carbon-sulfur composite as well as conductivity measurements were missed in the abstract. Please revise this section.

 Respond: This abstract section has been improved by adding experimental methods and characterization, including experimental processes for the production of activated carbon, preparation of activated carbon-sulfur composite and conductivity measurements. 

Reviewer 1:

Point 2. The new findings related to this work should be stated in the introduction clearly.

Respond: We have added the state of the art in the introduction especially regarding new finding. We add some sentences including the use of WH as activated carbon which is applied for cathode composite components of Li-S battery which is a new finding that has not been reported. 

Reviewer 1:

Point 3. The state of the art needs to be described more in the introduction. This information could help to show the lack of knowledge in the author's field of research.

Respond: We have revised some parts in the introduction to make the state of the art clearer. We have added the following sentences; The carbon matrix for sulfur can be in the form of micro, meso, and macroporous carbon,  graphene, carbon nanotubes (CNT), and also polymers. Although significant improvements to battery performance stability have been achieved, the process of synthesizing carbon materials, such as: graphite, graphene, CNT, and polymer requires high costs. Therefore, an effective and low-cost carbon matrix manufacturing strategy is needed to make high-performance of carbon matrix for sulfur.

Reviewer 1:

Point 4. Authors must show which questions/problems have been answered in this work. In this case, the correct and detailed definition of the volumetric 43 changes during the charge and discharge process must be provided in this manuscript.

 Respond: We have revised the sentence regarding volumetric expansion in introduction with the following sentences; The second problem at the cathode is the large volumetric expansion of sulfur upon lithiation caused by of the density difference between sulfur and lithium sulfide (2.03 and 1.66 g/cm3, respectively), sulfur has a larger volume expansion rate when it is become lithium sulfide completely, which may lead to the fracture and damage of the electrode..

Reviewer 1:

Point 5. Please provide the manufacturer/model/code and also the manufacturer country of the raw materials as well as all testing equipment used for evaluations.

 Respond: We have revised and added the specification of raw materials including the specification of equipment for characterization. All explanation are added in material and method section. 

Reviewer 1:

Point 6. It is beneficial to provide more information about Conductivity measurement in section 2.3.

 Respond: We have added complete information about methods of measuring electrical conductivity including technique (four-line probe) and equipment.

 

Reviewer 1:

Point 7. A step-by-step flowchart is beneficial to provide useful information in experimental processes.

 Respond: We have revised and added detailed the experimental method sequentially from the initial step to characterization. We divided the experimental process into four parts; 2.1 Synthesis of activated carbon, 2.2 Preparation of activated carbon-sulfur composite, 2.3 Characterization, 2.4 Conductivity measurement.

Reviewer 1:

Point 8. Detailed comments are required for this statement: “AC samples exhibited a pore distribution at above 2 nm, corresponding to high amounts of mesopores. The adsorption behavior on mesoporous is in the form of multilayer adsorption followed by pore condensation which describes the vapor to liquid phase transition, which is determined by the interaction of the sample with the gas and also by the interactions between the adsorbate molecules in the condensed state [28].”.

 Respond: We have revised and replaced the statement of  “AC samples exhibited a pore distribution at above 2 nm, corresponding to high amounts of mesopores. The adsorption behavior on mesoporous is in the form of multilayer adsorption followed by pore condensation which describes the vapor to liquid phase transition, which is determined by the interaction of the sample with the gas and also by the interactions between the adsorbate molecules in the condensed state [28]”, with a statement of “Figure 1(b) shows the graph of pore diameter versus dV/dD based on the Barrett–Joyner–Halenda (BJH) method. It is found that the pore size ranges are dominantly between 2 and 50 nm which indicates that the sample is a mesoporous type [27]”. 

Reviewer 1:

Point 9. In this manuscript, results are well presented, but discussion on the obtained results must be completely provided in this manuscript. As can be seen, a “comprehensive” and “comparative” discussion (e.g, for experimental data in Conductivity measurement and XRD phase detection) are missed in this work. This should be provided as well.

 Respond: We add an explanation and discussion of the relationship between the results of the conductivity measurements and the results of the XRD and TGA measurements. We have added sentences at the end of the results and discussion sections as follows; “When comparing the results of the electrical conductivity measurements for both ACWH-600 and ACWH-600/S with the crystal structures of these two materials, it was found that they agreed with the results of the crystal structure analysis obtained from XRD measurements as shown in Figure 4 and TGA measurements in Figure 5. The presence of sulfur that was confirmed from the XRD and TGA measurements caused a decrease in the conductivity value. However, this decrease in value is still within the range of the acceptable value for cathode applications in batteries. In addition, the results of this study also indicated the success of synthesizing a carbon matrix from WH with a high sulfur content and was a good sign for the development of battery material from abundantly available biomass which will ensure the sustainability of its application”. 

Reviewer 1:

Point 10. Please provide ICDD reference codes for each detected phase in XRD tests.

 Respond:  We have included the COD-CIF reference code on the XRD tests. COD-CIF code No. 1000065 for graphite and COD-CIF No. 1011160 for sulfur. 

Reviewer 1:

Point 11. There is no description of the future plans for research in the first part of the “Conclusions” section. This should be completed in section 6.

 

Respond 11: We have added an explanation of future plans for this research. We put the explanation of this part of the future plan in the last paragraph in the conclusion section.

 

Reviewer 1:

Point 12. Recently published references are beneficial for this work. Please check and use new references focused on your work.

 

Respond 12: We have added some new references to increase the quality of our manuscript. We added new references published in 2020, 2018, and 2017 as follows; 

1. [18] Zheng, M.; Hu, Q.; Zhang, S.; Tang, H.; Li, L. and Pang, H. Macroporous Activated Carbon Derived from Rapeseed Shell for Lithium–Sulfur Batteries. Sci. 2017, 7, 1036, doi : 10.3390/app7101036.
2. [19] Wang, Z.; Zhang, X.; Liu, X.; Zhang, Y.; Zhao, W.; Li, Y.; Qin, C.; Bakenov, Z. High specific surface area bimodal porous carbon derived from biomass reed flowers for high performance lithium-sulfur batteries. Journal of Colloid and Interface Science 2020, 569, 22–33, doi.org/10.1016/j.jcis.2020.02.062.
3. [20] Liang, J.; Tang, D.; Huang, L.; Chen, Y.; Ren, W.; Sun, J. High oxygen reduction reaction performance nitrogen-doped biochar cathode: A strategy for comprehensive utilizing nitrogen and carbon in water hyacinth. Bioresource Technology 2018, 267, 524–531, org/10.1016/j.biortech.2018.07.085.

 

Reviewer 1:

Point 13. Also, please double-check and revise the reference list according to the journal requirements.

 

Respond 13: We have re-checked and revised the reference list according to the journal requirements.

Reviewer 1:

Point 14. The English of this manuscript needs to be improved. Please check and revise the English language of the main text of the manuscript and also figure/table captions.

 

Respond 14: We have re-checked and revised the English language of the main text of the manuscript and also figure/table captions. We have also done English editing at a professional English Proofreading Service.

Author Response File: Author Response.pdf

Reviewer 2 Report

Attached are my remarks

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 an active carbon material made into composites for cathode applications in lithium-sulfur batteries. We found that the high sulfur content in the composite activated charcoal from water hyacinth which was carbonized at a temperature of 600 ^oC with ZnCl₂ activator with ratio 1:3, which indicates that activated carbon from biomass is also able to compete with other popular types of carbon materials with large surface area and pore volume and high electrical conductivity. This study is important to be reported as one of the results of research to obtain environmentally friendly battery materials derived from abundant and not optimally utilized biomass. Therefore, we hope an acceptance of our paper for publishing in the 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:

The work of Nurhilal et al. is interesting as it aims at a potential high sulfur source for batteries using activated carbon made from water hyacinth carbonized in the presence of ZnCl₂.

 

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

Reviewer 2:

Point 1. The title is representative but the abstract should be made in a more fluent form.

 Respond: We have improved the abstract section and added experimental methods, characterization, important results and future applications of carbon from WH. 

Reviewer 2:

Point 2. The introduction is well written, well cited.

 

Respond: Authors would like to thank for valuable comments. To increase the quality of our manuscript we added some additional information and references.

 

Reviewer 2:

Point 3. Materials and methods

2.4 Characterization

State the protocols used, clearly in a step by step manner

 Respond: We have revised the content of materials and methods section. We have added the specification of raw materials including the specification of equipment for characterization. We have also added detailed the experimental method sequentially from the initial step to characterization. We divided the experimental process into four parts; 2.1 Synthesis of activated carbon, 2.2 Preparation of activated carbon-sulfur composite, 2.3 Characterization, 2.4 Conductivity measurement.

Reviewer 2:

Point 4. Results and Discussion

They should be separated in 2 chapters for better clarity

 

Respond: Authors would like to thank for valuable suggestions. We have re-arranged the explanations for the results and discussion sections in order to better clarity. However, we still put the results and discussions in one section so that the discussion of each data can be directly observed and discussed properly.

 

Reviewer 2:

Point 5. Line 122-32 needs reformulation into a clearer more fluent form

 Respond: We have revised discussion in line 122-132. We have improved figure 1 to make it easier to understand and read. We have also corrected the explanation for figure 1 as follows; “The pore structure of the AC samples was analyzed by the N₂ isotherm adsorption-desorption method. Figure 1(a) shows relative pressure (P/Po) dependence of volume adsorbed for ACWH-400 (black circle for adsorption and purple circle for desorption) and ACWH-600 (blue circle for adsorption and red circle for desorption). It is found that the absorption of N₂ gas increased with increasing P/P_o and desorption of N₂ gas decreased with decreasing P/P_o for both samples. The values of volume adsorbed of ACWH-400 were smaller than that of ACWH-600, indicating that the carbonization process at a temperature of 600 ^oC produces more carbon than the carbonization process at a temperature of 400 ^oC. In both samples, hysteresis patterns were also found for the adsorption and desorption curves in the P/P_o range between 0.2-0.9. Figure 1(b) shows the graph of pore diameter versus dV/dD based on the Barrett–Joyner–Halenda (BJH) method. It is found that the pore size ranges are dominantly between 2 and 50 nm which indicates that the sample is a mesoporous type [27]”.

 

Reviewer 2:

Point 6. Conclusions are well written.

 

Respond: Authors would like to thank for valuable comments. To increase the quality of our manuscript, we have added an explanation of future plans for this research. We put the explanation of this part of the future plan in the last paragraph in the conclusion section.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The revised paper looks fine but minor issues still exist and must be corrected:

1- The name of the last author on the first page is incorrect. One of the name/last name is missed for "Risdiana2". Please check and revise.

2- The XRD result presented in Fig. 7 is repeated again from the previous page (Fig. 5) without figure caption and must be deleted from the manuscript.

3- Structural and morphological characteristics of the ACWH600, and ACWH600/S, materials must be provided in Fig. 2. For instance: the spongy surface, porous surface, rougher or finer surface, ... must be included in the sub-figures of Fig. 2 by arrows and textboxes. 

   

Author Response

Round 2

Respond to Reviewer 1 Comments

 

Dear the reviewer,

We reported a study on the use of biomass, namely water hyacinth as an active carbon material made into composites for cathode applications in lithium-sulfur batteries. We found that the high sulfur content in the composite activated charcoal from water hyacinth which was carbonized at a temperature of 600 ^oC with ZnCl₂ activator with ratio 1:3, which indicates that activated carbon from biomass is also able to compete with other popular types of carbon materials with large surface area and pore volume and high electrical conductivity. This study is important to be reported as one of the results of research to obtain environmentally friendly battery materials derived from abundant and not optimally utilized biomass. Therefore, we hope an acceptance of our paper for publishing in the 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: The revised paper looks fine but minor issues still exist and must be corrected.

 

Respond:

Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript. We have also re-checked details of the English language in the manuscript so that English is according to publication standards.

 

Reviewer 1

Point 1. The name of the last author on the first page is incorrect. One of the name/last name is missed for "Risdiana2". Please check and revise.

 Respond point 1: For the author's name "Risdiana", actually formally he only has one name and no last name, please check Scopus ID Risdiana: https://www.scopus.com/authid/detail.uri?authorId=25633171800. It is very common in Indonesia to have only one syllable in a name without including the last name or family name. However, if it must be written in two syllables, usually the author of "Risdiana" writes it twice as "Risdiana Risdiana". We have revised the author names of “Risdiana” to “Risdiana Risdiana”.  Reviewer 1

Point 2. The XRD result presented in Fig. 7 is repeated again from the previous page (Fig. 5) without figure caption and must be deleted from the manuscript.

 

Respond point 2: We have revised the figure caption. The figure caption has been adjusted to the caption template. We also re-check all explanations for all figures so that there is no unnecessary repetition of explanations in the manuscript.

 

Reviewer 1

Point 3. Structural and morphological characteristics of the ACWH600, and ACWH600/S, materials must be provided in Fig. 2. For instance: the spongy surface, porous surface, rougher or finer surface, must be included in the sub-figures of Fig. 2 by arrows and textboxes

 

Respond point 3: We have revised the structural and morphological characteristics in Figure 2 by adding arrows and text boxes, explaining the spongy surface position in Figure 2(a) and Figure 2(b).

 

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have greatly improved their manuscript.

The abstract is now clearer

Materials and methods have been revised with the much needed information of protocols and other critical details. Although the results and discussions were not separated in two different chapters as requested, they’ve been delimited.

The overall quality has been improved.

Author Response

Round 2

Respond to Reviewer 2 Comments

 

Dear the reviewer,

 We reported a study on the use of biomass, namely water hyacinth as an active carbon material made into composites for cathode applications in lithium-sulfur batteries. We found that the high sulfur content in the composite activated charcoal from water hyacinth which was carbonized at a temperature of 600 ^oC with ZnCl₂ activator with ratio 1:3, which indicates that activated carbon from biomass is also able to compete with other popular types of carbon materials with large surface area and pore volume and high electrical conductivity. This study is important to be reported as one of the results of research to obtain environmentally friendly battery materials derived from abundant and not optimally utilized biomass. Therefore, we hope an acceptance of our paper for publishing in the 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

Point 1. The authors have greatly improved their manuscript.

 

Respond point 1:

Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript. We have also re-checked details of the English language in the manuscript so that English is according to publication standards.

 

Reviewer 2

Point 2. The abstract is now clearer

 

Respond point 2:

Authors would like to thank you for the excellent response.

 

Reviewer 2

Point 3. Materials and methods have been revised with the much needed information of protocols and other critical details. Although the results and discussions were not separated in two different chapters as requested, they’ve been delimited.

 

Respond point 3:

We would like to thank you for the valuable comments regarding the “results and discussion” sections in chapter 3.

 

Reviewer 2

Point 4. The overall quality has been improved.

 

Respond point 4: Authors would like to thank for valuable comments and suggestions to increase the quality of our manuscript. 

Author Response File: Author Response.docx