A Study on Poly(ethylene oxide)-Based Supercapacitors Doped with Various Dopants
Round 1
Reviewer 1 Report
In this study, flexible polyester fabrics metalized by copper electroless plating were used to dope with different amounts of LiClO4 and different type of nanocarbons to form a series of new supercapacitors. The manuscript is well written. It will be interesting for scientific community.
I can recommend one for publication after some corrections.
The introduction does not contain any reference on other paper where textile-like material is used for supercapacitors.
The paper contain many data on the supercapacitor parameters measured by authors. However, there is no any comparison with the parameters obtained by other groups for similar supercapacitors.
“40 mg of each type of nanocarbons was dissolved into 10 ml of deionized water, then these nanocarbons solutions were sonicated by ultrasonic generator for two hours, to make sur these nanocarbons were dispersed well in each of the solutions without any aggregates being formed” Carbon nanomaterials is hydrophobic and cannot be dissolved in water without surfactant or functionalization. Usually, maximal possible concentration of the carbon nanotubes in suspension is about 0.1 mg per ml. I suppose that the authors obtain very unstable suspension with very large-size carbon agglomerates. Please, comment.
Author Response
In this study, flexible polyester fabrics metalized by copper electroless plating were used to dope with different amounts of LiClO4 and different type of nanocarbons to form a series of new supercapacitors. The manuscript is well written. It will be interesting for scientific community.
I can recommend one for publication after some corrections.
Q1.1 The introduction does not contain any reference on other paper where textile-like material is used for supercapacitors.
Reply: To enrich the reference on textile-like material being used for supercapacitors, some journal paper references have been added into the introduction [Ref: revision with new journal paper references in Line 52].
Q1.2 The paper contain many data on the supercapacitor parameters measured by authors. However, there is no any comparison with the parameters obtained by other groups for similar supercapacitors.
Reply: Yes, practically there is a bit difficult to find related references to compare, as the materials used and parameters measured are not matched in other researchers reports, so we can only provide few of them in the revision [Ref: revision in Line 490 and Line 654].
Q1.3 “40 mg of each type of nanocarbons was dissolved into 10 ml of deionized water, then these nanocarbons solutions were sonicated by ultrasonic generator for two hours, to make sur these nanocarbons were dispersed well in each of the solutions without any aggregates being formed” Carbon nanomaterials is hydrophobic and cannot be dissolved in water without surfactant or functionalization. Usually, maximal possible concentration of the carbon nanotubes in suspension is about 0.1 mg per ml. I suppose that the authors obtain very unstable suspension with very large-size carbon agglomerates. Please, comment.
Reply: Yes, some experimental conditions have to be clarified. First of all, the composition of PEO:nanocarbons is 5:1, where 200 mg PEO powder has dissolved in 10 ml of deionized water [Ref: revision in Line 187] and 40 mg nanocarbons has dissolved in 10 ml of deionized water, an additional information has been added to avoid misleading.
Besides, reviewer suggests about the unstable suspension is generally correct, but in our experiment, after some different trials on compositions and film-forming methods, we found that in this composition, nanocarbons can spread uniformly in the PEO colloidal dispersion and formed a uniformly spread layer casted on metallized polyester fabric without large-size carbon agglomerates. By testing tens of samples in each composition, we found that the data are consistent and so we accepted these data are reliable.
Reviewer 2 Report
The article submitted for review is devoted to the study of the specific characteristics of supercapacitors with electrodes based on copper-coated polyester and Li+ doped polyethylene oxide and various types of nanotubes and porous carbon powder. The topic of the article is relevant, but does not fully correspond to the profile of the Coatings magazine, since most of the material in the article is devoted to the study of the specific characteristics of a supercapacitor. This article is more relevant to the subject of Energy magazine (MDPI).
In my opinion, figure 2 can be excluded from the article, only a textual description of the cell scheme for electrochemical deposition of a copper coating is sufficient.
It is also necessary to cycle the supercapacitor to assess the safety of the capacitance.
Author Response
The article submitted for review is devoted to the study of the specific characteristics of supercapacitors with electrodes based on copper-coated polyester and Li+ doped polyethylene oxide and various types of nanotubes and porous carbon powder. The topic of the article is relevant, but does not fully correspond to the profile of the Coatings magazine, since most of the material in the article is devoted to the study of the specific characteristics of a supercapacitor. This article is more relevant to the subject of Energy magazine (MDPI).
Q2.1 In my opinion, figure 2 can be excluded from the article, only a textual description of the cell scheme for electrochemical deposition of a copper coating is sufficient.
Reply: We agree with the reviewer, and figure 2 has been removed.
Q2.2 It is also necessary to cycle the supercapacitor to assess the safety of the capacitance.
Reply: Technically speaking, PEO based supercapacitor is comparably safer than many types of supercapacitors, there is no risk to get explosion or catch fire, usually it will just degrade and cannot be charged up. Actually, we have tested tens of samples in each combination and more than hundred cycles in each sample, only sample degradation being observed.
Reviewer 3 Report
The manuscript reports poly(ethylene oxide)-based supercapacitors doped with various dopants. The work is interesting. The data analysis could basically support the authors' conclusion. The article could be accepted for publication after major revision towards the following questions.
1. The novelty of this work should be further highlighted in the Introduction part.
2. Some figures are suggested to be combined.
3. The reaction mechanism for the enhanced activity is unclear.
no
Author Response
The manuscript reports poly(ethylene oxide)-based supercapacitors doped with various dopants. The work is interesting. The data analysis could basically support the authors' conclusion. The article could be accepted for publication after major revision towards the following questions.
Q3.1 The novelty of this work should be further highlighted in the Introduction part.
Reply: In the past decades, researchers have contributed their efforts in different researches with LiClO4 and nanocarbons in different electrical properties, such as current density and specific capacitance. Many of them are using volatile chemicals as solvents to prepare the PEO:Li+ or PEO:nanocarbons layers due to their high dissolving power. However, the residue of these solvents may remain in samples after preparation, which is not good to human. If this fabric-based supercapacitor is proposed to be worn by human or even closely touch on human skin, the materials/chemicals used to build up this supercapacitor system have to be carefully considered. Therefore, we only use water to dissolve LiClO4 and nanocarbons in our experiment and solution casted them on metallized polyester fabrics, seems similar researches are rarely found [Ref: Revision with adding solvent consideration in Line 70].
Q3.2 Some figures are suggested to be combined.
Reply: Yes, schematic diagrams for showing various PEO:Li+ and PEO:nanocarbons solutions casted on the polyester fabrics have been combined together [Ref: new Figure 2].
Q3.3 The reaction mechanism for the enhanced activity is unclear.
Reply: Yes, the enhancement of charge capability seems a bit vague, we have revised it and hope readers can easily understand [Ref: Revision with clear explanation in Line 295].
Reviewer 4 Report
This paper describes synthesis and characterization of PEO-based electrochemical double layer (EDL) supercapacitors doped with LiClO4 and nanocarbons. Increases of maximum current density and specific capacitance are noted in the presence of LiClO4 and nanocarbons. Unfortunately, novelty of this work is not clearly described.
Combination of supercapacitors and electro-textiles is new?
Increases of current density and specific capacitance by added LiClO4 and nanocarbons was not known before?
How good is the present results compared to other methods?
Although many experimental data are provided, purpose of these experiments and evaluation of the results are often not clearly shown.
Conclusion notes that presence of LiClO4 and nanocarbons show higher specific capacitance and maximum current density, and then what are other experiments?
This paper cannot be recommended for publication in Coating in its present form.
An additional comment: what lines mean in Figures 8, 10, 11, and other related? Is frequency changed continuously?
Author Response
This paper describes synthesis and characterization of PEO-based electrochemical double layer (EDL) supercapacitors doped with LiClO4 and nanocarbons. Increases of maximum current density and specific capacitance are noted in the presence of LiClO4 and nanocarbons. Unfortunately, novelty of this work is not clearly described.
Q4.1 Combination of supercapacitors and electro-textiles is new?
Reply: In this two decades, combination of supercapacitors and electro-textiles have drawn researchers attention due to their large developing opportunities, the increase of medical application needs, and the potential of device sustainability. Though the research field cannot be said as “new”, they are responding to current needs and worth to be done.
Q4.2 Increases of current density and specific capacitance by added LiClO4 and nanocarbons was not known before?
Reply: In the past decades, researchers have contributed their efforts in different researches with LiClO4 and nanocarbons in different electrical properties, such as current density and specific capacitance. Many of them are using volatile chemicals as solvents to prepare the PEO:Li+ or PEO:nanocarbons layers due to their high dissolving power. However, the residue of these solvents may remain in samples after preparation, which is not good to human. If this fabric-based supercapacitor is proposed to be worn by human or even closely touch on human skin, the materials/chemicals used to build up this supercapacitor system have to be carefully considered. Therefore, we only use water to dissolve LiClO4 and nanocarbons in our experiment and solution casted them on metallized polyester fabrics, seems similar researches are rarely found [Ref: Revision with adding solvent consideration in Line 70].
Q4.3 How good is the present results compared to other methods?
Reply: Yes, practically there is a bit difficult to find related references to compare, as the materials used and parameters measured are not matched in other researchers reports, so we can only provide few of them in the revision [Ref: revision in Line 490 and Line 654].
Q4.4 Although many experimental data are provided, purpose of these experiments and evaluation of the results are often not clearly shown.
Reply: Yes, a revision has been made in introduction to make the experiment purpose a bit clear [Ref: revision in Line 68]. Besides, some further explanations have been added to enrich the results evaluation [Ref: revision in Line 346 and Line 542].
Q4.5 Conclusion notes that presence of LiClO4 and nanocarbons show higher specific capacitance and maximum current density, and then what are other experiments?
Reply: In this study, we are only focus on demonstrating the electrical properties of different amount of LiClO4 and various type of nanocarbons, so other experiments will not show in this study currently.
Q4.6 This paper cannot be recommended for publication in Coating in its present form.
Reply: We revised the manuscript according to all reviewers' comments
Q4.7 An additional comment: what lines mean in Figures 8, 10, 11, and other related? Is frequency changed continuously?
Reply: Yes, in all frequency responses related figures, the frequency changed from 40 to 110 MHz continuously, and around 200 data points are recorded in each case. Those lines are representing the change to electrical properties along the change of frequency. To avoid misleading, I’ve changed the data lines into points for the ease of reference [Ref: new Figure 6, 8-12, 15-20].
Round 2
Reviewer 1 Report
I am not satisfied with the answer to my third question. Authors did not modify the controversial statement “For various PEO:nanocarbons solutions, 40 mg of each type of nanocarbons was 180 dissolved into 10 ml of deionized water, then these nanocarbons solutions were sonicated by ultrasonic generator for two hours, to make sur these nanocarbons were dispersed well in each of the solutions without any aggregates being formed.”
They say that “nanocarbons can spread uniformly in the PEO colloidal dispersion and formed a uniformly spread layer casted on metallized polyester fabric without large-size carbon agglomerates.”
What is the size of those agglomerates? The concentration of 4 mg/ml is too high to get stable suspension of individual tubes in water. I suspect that obtain suspension contain large-size agglomerates with the size of tens of micrometers. The size of agglomerates should be indicated in the text.
Author Response
Reply: We agree to reviewer’s comment, the phrase “to make sur these nanocarbons were dispersed well in each of the solutions without any aggregates being formed.” has been rewritten into “to help these nanocarbons dispersed in solutions.” to avoid any misleading.
[Ref: revision in Line 192].
Reviewer 2 Report
Article correctedAuthor Response
Thank you for support
Reviewer 3 Report
it can be accepted now
no
Author Response
Thank you for support
Reviewer 4 Report
Unfortunately, this referee considers that the revised manuscript still fails to describe implication of this work, and novelty of this work cannot be found. Publication in Coating then is not recommended. Reasonable comparison with their own works and related works by other researchers has not been made. Authors note it is difficult because materials and parameters are different, but it stands for all scientific studies. This referee believes that comparison is the basis of science.
Author Response
Reply: We agree to reviewer’s comment, additional paragraphs and a table of other researcher works have been added to compare other research groups works, hence the novelty of this study has been linked up in the following paragraph. [Ref: revision started from Line 66 to 76].
Besides, about “the implication of this work”, a short paragraph is added [Ref: revision started from Line 686 to 691] and hope it can help readers to understand this work.
Round 3
Reviewer 1 Report
I can recommend this paper for publication
Reviewer 4 Report
The revised manuscript is acceptable for publication.
