Active Carbon Modified by Rhenium Species as a Perspective Supercapacitor Electrode
, Andrzej Koszorek 2, Łukasz Hawełek 3, Małgorzata Osadnik 4, Katarzyna Szleper 5 and Michał Drzazga 1Round 1
Reviewer 1 Report
The manuscript describes the combination of amorphous Re with active carbon for supercapacitor application. However, the reviewer feels the manuscript is not solid in the current form. The characterization and testing of the materials are not sufficient. The description and explanation of the data are poor.
The current XRD is not enough to support the formation of Re. More characterization of the formation of Re is required, such as XPS. The redox state of Re needs to be clarify.
CVs of three different samples in Figure 3 show identical current, showing no difference on the capacitance of the such samples. This is conflict with the GCD test. This is the main flaw of this work.
Rct values should be given for different samples for a clear comparison.
English needs to be improved.
Author Response
Reviewer 1
The manuscript describes the combination of amorphous Re with active carbon for supercapacitor application. However, the reviewer feels the manuscript is not solid in the current form. The characterization and testing of the materials are not sufficient. The description and explanation of the data are poor.
The current XRD is not enough to support the formation of Re. More characterization of the formation of Re is required, such as XPS. The redox state of Re needs to be clarify.
CVs of three different samples in Figure 3 show identical current, showing no difference on the capacitance of the such samples. This is conflict with the GCD test. This is the main flaw of this work.
Rct values should be given for different samples for a clear comparison.
English needs to be improved.
ANSWER: We have prepared material once again with an increased amount of reducing agent and longer reaction time. Consequently, XRD analysis revealed several signals which were attributed to rhenium species. Unfortunately we are unable to perform XPS analysis.
CV curves are very similar indeed, and these differences are in fact really small. However, CV analysis is performed more to define stability/cyclability of the specific material. While capacitance value was calculated from galvanostatic charge discharge curves. One important thing in case of rhenium modified carbon CVs is the fact of faster charging and discharging modes that can be observe in a fig. 3 (smoother edges for AC-Re).
The charge transfer resistance values were calculated and added within the text.
English language was spell-checked and grammar errors were corrected.
Reviewer 2 Report
In their paper “Active carbon modified by rhenium species as a perspective supercapacitor electrode” the author reported the composite materials of the Rhenium and carbon-based supercapacitor. Ciszewski et. al. mentioned the wet impregnation synthesis of the materials and the characterization has performed via XRD, BET, and SEM. Whereas, electrochemical characterization has performed to evaluate the supercapacitor properties such as CV, Nyquist plots, charge-discharge behavior.
Comments
- A minor revision with better analysis, clear data and more relevant introduction is recommended. Some sentence formation are unclear and confusing in the manuscript.
- The author should increase the font of the SEM image
- XRD peak planes are missing
Author Response
Minor errors were corrected. Analysis of the materials was repeated and improved as well.
Reviewer 3 Report
The authors reported on the preparation of Re-modified active carbon electrode. The electrode was characterized by SEM, XRD and BET analyses. The pseudocapacitive properties of the electrode where evaluated by cyclic voltammetry, galvanostatic charge-discharge tests and EIS, and compared to those of the bare active carbon and oxidized active carbon electrodes. However, the superior energy storage ability of Re-modified active carbon has not been properly presented and discussed. Also, moderate editing of English language and style is required. Therefore, I recommend the publication of this article in Electrochem only after a major revision as follows:
1) Editing of English language and style. The manuscript presents many mistakes, such as
- Chargé (page 1, abstract, line 6; page 2, line 11; page 6, 2nd paragraph, line 2; caption Figure 3) instead of charge
- Condition (page 1, 1st paragraph of the introduction, line 6) instead of conditioning
- Comounds (page 2, 2nd paragraph of the introduction, line 3) instead of compounds
- Examine (page 2, 2nd paragraph of the introduction, line 4) instead of examined
- Irraditaion (page 2, 2nd paragraph of the introduction, line 15) instead of irradiation
- Desorpion (page 3, 1st paragraph of results, line 2) instead of desorption
- EM (page 4, line 1) instead of SEM
- Mpregnated (page 4, line 6) instead of impregnated
- Obsered (page 6, 2nd paragraph, line 12) instead of observed
- Oamount (page 8, line 4) instead of amount
2) Please specify the applied potential used for EIS experiments in the “Characterization” section. Is it 0 V vs open circuit potential?
3) The authors presented the energy storage ability of the tested electrodes in terms of specific capacity [F/g]. However, the term specific capacity refers to battery-type electrodes (NiO and Ni(OH)2 for example) where it is not possible to define a capacitance. In this case the charge stored is expressed by the specific capacity [mAh/g] or [C/g]. For capacitive electrodes (EDLCs and pseudocapacitors), capacitance can be defined and specific capacitance [F/g] should be used. This is clearly explained in the following references:
- [ref1] Simon, P., Gogotsi, Y., & Dunn, B. (2014). Where do batteries end and supercapacitors begin?. Science, 343(6176), 1210-1211.
- [ref2] Brousse, T., Bélanger, D., & Long, J. W. (2015). To be or not to be pseudocapacitive?. Journal of The Electrochemical Society, 162(5), A5185-A5189.
- [ref3] Brisse, A. L., Stevens, P., Toussaint, G., Crosnier, O., & Brousse, T. (2018). Ni(OH)2 and NiO based composites: battery type electrode materials for hybrid supercapacitor devices. Materials, 11(7), 1178.
- [ref4] Urso, M., Torrisi, G., Boninelli, S., Bongiorno, C., Priolo, F., & Mirabella, S. (2019). Ni(OH)2@Ni core-shell nanochains as low-cost high-rate performance electrode for energy storage applications. Scientific reports, 9(1), 1-11.
Therefore, please substitute all “capacity” in the manuscript with “capacitance”.
4) The mass loading [g/cm2] of the three electrodes (active carbon, oxidized active carbon and Re-modified active carbon) should be reported in the experimental section.
In fact, authors said “Difference in masses between AC-ox and AC-Re (regardless oxygen species desorpion combined with reduction) and quantitative analysis of rhenium in post-sorption solution showed that rhenium species was successfully impregnated into the carbon.” in page 3, 1st paragraph.
Moreover, these data are relevant for specific capacitance estimation and therefore they should be available.
5) Figure 3 needs some serious reworks as follows.
- In Figure 3 the authors presented 1000 cycles of CV for the three tested electrodes as current (A) vs voltage (V). From this figure it is not clear that Re-modified active carbon stores more charge than the other two. I recommend to remove or transfer these CVs in the supplementary data, and replace them with a comparison of the first CV cycle of the three electrodes as current density (A/g) vs voltage (V). In this way, the superior energy storage ability of the Re-modified electrode should be observed as a rectangular CV with larger area than the other electrodes.
- I also suggest to clearly state that this rectangular CV shaper is characteristic of a pseudocapacitive material, rather than a battery material, as clearly reported in the above mentioned [ref1-4].
- % specific capacity drop vs cycle number should be replaced with specific capacitance [F/g] vs cycle number, to clearly present the specific capacitance values after 1000 cycles, as in [ref4]. In fact, the figure presented by authors does not clearly evidence that, despite after 1000 cycles the three electrodes have almost the same % specific capacitance drop, the specific capacitance of Re-modified electrode is still higher than other since due to its higher initial value.
- The authors should clearly indicate the scan rate of CVs and current density of charge-discharge tests in the caption of Figure 3.
- The authors performed charge-discharge tests at various current densities, but these data are not clearly reported and discussed. I suggest to show at least the specific capacitance [F/g] vs current density [A/g] for the three electrodes, as shown in the above mentioned [ref4]. In this way, the rate capability, i.e. the ability to retain the initial specific capacitance even at fast charge-discharge rate, of the three electrodes can be estimated and compared. This is a very important aspect for hybrid supercapacitors applications.
6) Regarding the discussion of the EIS spectra, the authors wrote “The imaginary vs real impedance relations which can be seen on Nyquist plot indicated lower resistance for AC-ox and AC-Re”. However, it seems that AC-Re has larger intercept on the real axis (solution resistance) and larger semicircle arc (charge transfer resistance). Therefore, the authors should better motivate these differences.
7) The are basically no references in “Results” section to support the discussion of the experimental results. Therefore, more references should be appropriately added to this section. Furthermore, a comparison with other recent (last 2 years) energy storage materials (rate capability, cycle life, etc.) should be also reported.
Author Response
1) Editing of English language and style. The manuscript presents many mistakes, such as
Chargé (page 1, abstract, line 6; page 2, line 11; page 6, 2nd paragraph, line 2; caption Figure 3) instead of charge
Condition (page 1, 1st paragraph of the introduction, line 6) instead of conditioning
Comounds (page 2, 2nd paragraph of the introduction, line 3) instead of compounds
Examine (page 2, 2nd paragraph of the introduction, line 4) instead of examined
Irraditaion (page 2, 2nd paragraph of the introduction, line 15) instead of irradiation
Desorpion (page 3, 1st paragraph of results, line 2) instead of desorption
EM (page 4, line 1) instead of SEM
Mpregnated (page 4, line 6) instead of impregnated
Obsered (page 6, 2nd paragraph, line 12) instead of observed
Oamount (page 8, line 4) instead of amount
Answer: All errors were corrected.
2) Please specify the applied potential used for EIS experiments in the “Characterization” section. Is it 0 V vs open circuit potential?
Answer: This data was added. The applied potential was 0V.
3) The authors presented the energy storage ability of the tested electrodes in terms of specific capacity [F/g]. However, the term specific capacity refers to battery-type electrodes (NiO and Ni(OH)2 for example) where it is not possible to define a capacitance. In this case the charge stored is expressed by the specific capacity [mAh/g] or [C/g]. For capacitive electrodes (EDLCs and pseudocapacitors), capacitance can be defined and specific capacitance [F/g] should be used. This is clearly explained in the following references:
[ref1] Simon, P., Gogotsi, Y., & Dunn, B. (2014). Where do batteries end and supercapacitors begin?. Science, 343(6176), 1210-1211.
[ref2] Brousse, T., Bélanger, D., & Long, J. W. (2015). To be or not to be pseudocapacitive?. Journal of The Electrochemical Society, 162(5), A5185-A5189.
[ref3] Brisse, A. L., Stevens, P., Toussaint, G., Crosnier, O., & Brousse, T. (2018). Ni(OH)2 and NiO based composites: battery type electrode materials for hybrid supercapacitor devices. Materials, 11(7), 1178.
[ref4] Urso, M., Torrisi, G., Boninelli, S., Bongiorno, C., Priolo, F., & Mirabella, S. (2019). Ni(OH)2@Ni core-shell nanochains as low-cost high-rate performance electrode for energy storage applications. Scientific reports, 9(1), 1-11.
Therefore, please substitute all “capacity” in the manuscript with “capacitance”.
Answer: We have read this papers and all these data were corrected.
4) The mass loading [g/cm2] of the three electrodes (active carbon, oxidized active carbon and Re-modified active carbon) should be reported in the experimental section.
Answer: This was added in experimental part
In fact, authors said “Difference in masses between AC-ox and AC-Re (regardless oxygen species desorpion combined with reduction) and quantitative analysis of rhenium in post-sorption solution showed that rhenium species was successfully impregnated into the carbon.” in page 3, 1st paragraph.
Answer: The experimental part was repeated for the composite. We have used bigger amount of reducing agent and longer reaction time. Consequently, repeated XRD analysis allowed to observe additional signals which were attributed to ammonium perrhenate
5) Figure 3 needs some serious reworks as follows.
In Figure 3 the authors presented 1000 cycles of CV for the three tested electrodes as current (A) vs voltage (V). From this figure it is not clear that Re-modified active carbon stores more charge than the other two. I recommend to remove or transfer these CVs in the supplementary data, and replace them with a comparison of the first CV cycle of the three electrodes as current density (A/g) vs voltage (V). In this way, the superior energy storage ability of the Re-modified electrode should be observed as a rectangular CV with larger area than the other electrodes.
I also suggest to clearly state that this rectangular CV shaper is characteristic of a pseudocapacitive material, rather than a battery material, as clearly reported in the above mentioned [ref1-4].
% specific capacity drop vs cycle number should be replaced with specific capacitance [F/g] vs cycle number, to clearly present the specific capacitance values after 1000 cycles, as in [ref4]. In fact, the figure presented by authors does not clearly evidence that, despite after 1000 cycles the three electrodes have almost the same % specific capacitance drop, the specific capacitance of Re-modified electrode is still higher than other since due to its higher initial value.
The authors should clearly indicate the scan rate of CVs and current density of charge-discharge tests in the caption of Figure 3.
The authors performed charge-discharge tests at various current densities, but these data are not clearly reported and discussed. I suggest to show at least the specific capacitance [F/g] vs current density [A/g] for the three electrodes, as shown in the above mentioned [ref4]. In this way, the rate capability, i.e. the ability to retain the initial specific capacitance even at fast charge-discharge rate, of the three electrodes can be estimated and compared. This is a very important aspect for hybrid supercapacitors applications.
Answer: The electrochemical part was strongly corrected. After additional analysis of we have focused on CV, GC/GD and Nyquist plots description. Relevant data like scan rate and current density were added (single value of current density was chosen).
6) Regarding the discussion of the EIS spectra, the authors wrote “The imaginary vs real impedance relations which can be seen on Nyquist plot indicated lower resistance for AC-ox and AC-Re”. However, it seems that AC-Re has larger intercept on the real axis (solution resistance) and larger semicircle arc (charge transfer resistance). Therefore, the authors should better motivate these differences.
Answer: After improved synthesis path this test was repeated and proper description was added.
7) The are basically no references in “Results” section to support the discussion of the experimental results. Therefore, more references should be appropriately added to this section. Furthermore, a comparison with other recent (last 2 years) energy storage materials (rate capability, cycle life, etc.) should be also reported.
Answer: We cannot agree with this point. Traditionally, I’m far away from inserting Refs in results part. If anything is needed I try to give description in introduction part.
Reviewer 4 Report
Active carbon modified by rhenium species as aperspective supercapacitor electrode
Mateusz etal
Authors studied the carbon modified rhenium composites for supercapacitor a, following revisions are needed to publish above paper in Electrochem
- Remove the capacitance values in decimal places
- Please mention weight of active material in mg/cm2 and geometrical area of the electrodes.
- Electroechemical discussion to improved based on previous literature effect of references electrodes, effect of electrolyte and its concentration on differences in the capacitance values , please mention the reference electrode ( V vs. --) ah
- Figs .3 : improved, give the number (a) , check the last fig y axis : -ve
- If u have any data on EIS data on fresh cell or cycled cell will be useful
- Authors must add few lines the advantages of oxides vs. carbon electrodes in terms of flat platux potentials, overall present present nice shapes it will be useful for real applications
- Introduction section to be further improved : few other super capacitor are missing (Energy & Fuels 34 (2020)5072, Journal of Colloid and Interface Science 562(2019)567, Langmuir, 34 (2018) 1873, Materials & Design 122(2017) 376)
Author Response
All the required data were added
Round 2
Reviewer 1 Report
The reviewer is OK with current form.
Author Response
Thank you
Reviewer 3 Report
The revised manuscript is improved. However it is not clear why the authors decided to not show the mass loading [g/cm2] of the three samples (AC, AC-ox and AC-Re) and the data on specific capacitance at different scan rates and at different current density despite they have carried out these measurements. These information are crucial. Therefore I believe that Figure 3 and its discussion must be improved as previously suggested, since this should be the core of the paper and of course the most interesting part for the readership of Electrochem.
Furthermore, a table comparing the AC-Re performances with other recent materials, must be reported, highlighting the advantages and disadvantages of the presented electrode material in terms of simplicity of preparation, specific capacitance/capacity, rate capability, stability, including at least:
[1] Cho, S., Kim, J., Jo, Y., Ahmed, A. T. A., Chavan, H. S., Woo, H., ... & Kim, H. (2017). Bendable RuO2/graphene thin film for fully flexible supercapacitor electrodes with superior stability. Journal of Alloys and Compounds, 725, 108-114.
[2] Veerakumar, P., Rajkumar, C., Chen, S. M., Thirumalraj, B., & Lin, K. C. (2018). Activated porous carbon supported rhenium composites as electrode materials for electrocatalytic and supercapacitor applications. Electrochimica Acta, 271, 433-447.
[3] Brisse, A. L., Stevens, P., Toussaint, G., Crosnier, O., & Brousse, T. (2018). Performance and limitations of Cu2O: Graphene composite electrode materials for aqueous hybrid electrochemical capacitors. Electrochimica Acta, 279, 161-167.
[4] Urso, M., Torrisi, G., Boninelli, S., Bongiorno, C., Priolo, F., & Mirabella, S. (2019). Ni (OH) 2@ Ni core-shell nanochains as low-cost high-rate performance electrode for energy storage applications. Scientific reports, 9(1), 1-11.
[5] Du, W., Wang, X., Zhan, J., Sun, X., Kang, L., Jiang, F., ... & Murugadoss, V. (2019). Biological cell template synthesis of nitrogen-doped porous hollow carbon spheres/MnO2 composites for high-performance asymmetric supercapacitors. Electrochimica Acta, 296, 907-915.
[6] Wei, S., Zhou, R., & Wang, G. (2019). Enhanced Electrochemical Performance of Self-Assembled Nanoflowers of MoS2 Nanosheets as Supercapacitor Electrode Materials. ACS omega, 4(14), 15780-15788.
This is important to understand how promising is the reported material and what can be done to further improve it.
Hence, I do not recommend the publication of the manuscript in the present form, but only after the author address these weak points.
Author Response
"The revised manuscript is improved. However it is not clear why the authors decided to not show the mass loading [g/cm2] of the three samples (AC, AC-ox and AC-Re) and the data on specific capacitance at different scan rates and at different current density despite they have carried out these measurements. These information are crucial. Therefore I believe that Figure 3 and its discussion must be improved as previously suggested, since this should be the core of the paper and of course the most interesting part for the readership of Electrochem."
Comment: I thought that the mass of active material was given within the text of revised manuscript (5mg) as well as the diameter of capacitor (25mm) so practically the mass loading can be easily calculated from it!
Specific capacity at different current density is not so crucial for me. The goal is to show how the capacitor behaves at fast scanning rate to establish its stability. Specific capacitance at different scan rates is not so crucial.
"Furthermore, a table comparing the AC-Re performances with other recent materials, must be reported, highlighting the advantages and disadvantages of the presented electrode material in terms of simplicity of preparation, specific capacitance/capacity, rate capability, stability, including at least:...."
Comment: Really? Table comparing materials (synthesis/properties)? This manuscript is not a review, rather communication. I hope that your willingness to add specific papers written with all datas for us does not have non-ethical background.
