The Electrochemical Performance of Al-Mg-Ga-Sn-xBi Alloy Used as the Anodic Material for Al-Air Battery in KOH Electrolytes
Round 1
Reviewer 1 Report
Reviewer thank authors for the invitation. The manuscript can be published but require major revision
Introduction should be more informative about other stratigies to improve the corrosion issues in Al based batteries. Authors should include articles Advanced Science, 2020, 7 (5), 1902866; J. Mater. Chem. A, 2022,10, 4601-4610; Materials Today Energy, 101064, 28, (101064), (2022)
Increase in HER by increasing Bi from 0.1 to 0.12 is actually higher than AlMgSnGa which is not well understood. Could authors provide HER using Bi?
Why did authors stopped at 220 min discharge? They should have tried to exmained for more time since its a primary battery demonstration. Also, the discharge profile should be explained better. There is a drop in potential and then potential get stabilize why?
Why did not authors exmained rechargability of Al-air battery?
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This is an interesting manuscript about the influence of Bi on the electrochemical properties of anodic material (Al-Mg-Ga-Sn alloy) in an Al-air battery. The article corresponds to the journal's specialization; however, the general impression is that certain parts of the manuscript are superficially presented with many ambiguities and need to be improved.
Throughout the entire manuscript
- There are so many typographical errors in the manuscript which must be corrected. For example, the sentences are not separated, i.e. no space after the dot (for example lines 22, 25, 30, etc. throughout the entire text). Please correct this.
- Lines 36, 40 (and in other places in the text): "...hydrogen precipitation.." it is better to use "..hydrogen evolution..".
- Line 38: "...into the Al Matrix.." should be ..." into the Al matrix..". Similar corrections should be made in other parts of the text.
- In the experimental part, the alloy is presented as Al-0.4Mg-0.015Sn-0.05Ga-xBi, and throughout the rest of the text, it is better to use the abbreviated name Al-Mg-Sn-Ga-xBi.
- The electrolyte is 6 M KOH or 6 mol/L KOH. Harmonize throughout the text.
- Remove the dot after figures and tables (for example Figure 3. should be Figure 3, etc.).
Abstract
- Line 15 “… 0.132 mL.cm-2.min-1 …”; without point.
1. Introduction
- "Aluminum has a theoretical energy density of 4300 Wh/g, second only to lithium (5200 Wh/g)". This claim should be verified and relevant literature cited. According to my knowledge, the theoretical energy density of aluminum is 8.1 kWh/kg.
- Line 43: "Hamed et al [21] demonstrated that Pb and Ga elements..." this statement does not correspond to the given reference.
- Line 45: "Ma et al [22]. reported that the addition of 0.1 wt.%Zn to Al-1Mg-0.1Sn-01Ga raised the discharge voltage and prevented the hydrogen evolution.” Check this claim or reference 22! Also, remove the dot after [22].
- References listed in the Introduction section, like 9, 11, 12, 15, 23, 27 are repeated. Please remove duplicates from the list of references and make appropriate changes in the Introduction.
2. Experimental
- It is not clear whether the electrode materials are commercial, or whether the authors made them themselves. Please indicate that. Has the composition of the alloys been checked?
- The conditions for performing some measurements are unclear. Were all measurements performed at 45 oC (this is stated in the conclusion)? The conditions for self-corrosion measurements are not harmonized. Hydrogen evolution was measured for 90 min at 25 oC, OCP was monitored for 60 min (at what temperature?), potentiodynamic polarization measurements after the OCP had established (When? OCP is not stable after 1 h (Fig. 6). At what temperature?). On the other hand, EIS measurements were performed on OCP after 30 min at 45 oC. Why this diversity in experimental condition settings? In my opinion, this should all be harmonized (same stabilization time, same temperature).
- Battery performance tests were done at 45 oC. I guess there is a reason why the discharge measurements were performed at an elevated temperature. Please provide additional explanations for the results.
- Line 130: "The contact surface between the cathode and the anode is square (4 × 4 cm2), with a distance of 1 cm.". This is unclear. I guess the authors wanted to say that the surface of the electrodes is 4 cm x 4 cm and that they are located at a distance of 1 cm.
3. Results and discussion
- Line 152: "...when no bi(a) element..." should be "when no Bi (a) element..".
- It is not clear which alloy is described in Table 2, and positions 1-8 should be marked on the corresponding picture (or pictures).
- The influence of Bi on the effect of self-corrosion inhibition and activation of aluminum alloys (in battery performance test) is interpreted by the authors in the same way, i.e. as a high overvoltage of hydrogen evolution due to the presence of Bi. However, these are two completely opposite processes and should have different explanations. Namely, the authors should provide an additional and precise explanation for the active dissolution of the alloy (perhaps make a link with the EDS analysis).
- How is polarization resistance determined? No linear polarization measurement was performed, and Table 3 does not contain data for anodic and cathodic Tafel slopes.
- Table 5: Expand the first column, so that the rows align.
- Figure 10: "Power Density" rotates by 180o.
- Check picture 11! Maybe the increase in b), d), f) and h) is wrongly labeled.
4. Conclusion
- The conclusion is too general. Please rewrite and present the basic conclusions of the work.
- The conclusion stated under 1) has no basis in the work.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors have revised the manuscript well therefore, it can accepted in its current format.
Author Response
We would like to express our great appreciation to you and reviewers for comments on our paper. Looking forward to hearing from you.
Reviewer 2 Report
The revised version of the manuscript has been significantly improved. The manuscript can be published in Crystals after correcting minor errors:
- Authors names: “Yueying Wang1.2, ……” should be “Yueying Wang1, …”.
- “R” in the equation should be in italic form “R”.
- Line 117: “…hydrogen evolution rate (in mL/cm2 /min)…” shoul be “…hydrogen evolution rate (in mL/cm2 min)…”.
- Line 128: “…1 mV/S…” should be “….1 mv/s….”.
- Line 149: “..Q0 = 2980 Ah/Kg..” should be “..Q0 = 2980 Ah/kg..”.
- Line 192: “…the Al-Mg-Sn-Ga-xBi alloys, It can be…” should be “….“…the Al-Mg-Sn-Ga-xBi alloys. It can be…”.
- Lines 141-143; “…corrosion parameters, i.e., corrosion potential (Ecorr), corrosion current density (Jcorr) and polarization resistance (Rp)…” should be “…corrosion parameters, i.e., corrosion potential (Ecorr), corrosion current density (jcorr) and polarization resistance (Rp)…”.
- Check the authors' names on references 13 and 36; it is about the same authors (the authors' names are wrongly stated in one of the references).
Author Response
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Author Response File: 
Author Response.docx
