High-Performance Anodes Made of Metallic Lithium Layers and Lithiated Silicon Layers Prepared by Vacuum Technologies
Round 1
Reviewer 1 Report
The authors reviewed the recent progress of synthesis of heterocyclic compounds by electrochemical method. To some extent, this is a topic of interest to the researchers in the related areas and this paper can be published after some minor revisions. The following points require consideration:
(1) The importance and necessity of the work should be emphasized in the Introduction section.
(2) Further improvement in English is required. There are trivial grammatical errors in the text.”
(3) Please highlight the advantages and disadvantages of vacuum processing method.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
In this work, Stefan Saager et al. proposed an interesting PVD method to realize thin Li or Li-Si layer deposition, which may serve as a promising method for lithium metal batteries. The corresponding discussions are comprehensive and insightful. However, the evaluations on the electrochemical performance are quite limited. For example, the capacity is only ca. 0.5 mAh/cm2 in Figure 8, far less than the claimed 1-20 μm thickness considering the theoretical capacity of lithium (ca. 3860 mAh/g) and density (ca. 0.534 g/cm3). Therefore, the evaluations on electrochemical performance under a relative thick deposition depth like 10 μm, and evaluations on the electrochemical reversibility, are quite essential. Besides, the electrochemical evaluations on Li-Si layer are missing. With above issue well addressed, the reviewer would be glad to recommend it for publication in Batteries.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
The reviewer would like to thank the authors for the submission of their manuscript titled "High Performance Anodes Made of Metallic Lithium Layers and Lithiated Silicon Layers Prepared by Vacuum Technologies".
Vacuum deposition of lithium to create thin, uniform, defect free and contaminant free coatings is an active area of research that has a promising potential and requires in depth analysis and parameter control on the deposition. In this respect, the authors have provided a proof of concept work on how to enable lithium coatings and the influence of substrate pre treatment as well as clearly discuss challenges associated.
However the proposed idea on the advantages of porous lithium and lithiated silicon were not tested with a reference to show clear advantages and bold claims on large scale applicability have been made when major challenges as discussed in the manuscript still need to be addressed.
As such, the reviewer recommends major revisions before accepting the manuscript.
Detailed comments are as follows:
1. Overall, the reviewer recommends the focus of the manuscript to be changed towards lithium deposition and the influence of pre treatment on the lithium morphology. Porous lithiated silicon and associated advantages as mentioned in the introduction led to delamination issues and hence should be presented briefly, if at all, with only 1 figure as applicability of the proposed PVD technology to other systems and that more work is needed to address issues with silicon.
2. The reviewer recommends removing silicon from Figure 1 and to focus on lithium metal itself.
3. Section 2.2 Page 5 Line 170-185, can the authors provide additional details on how many cells were tested?
4. Section 3.2.2 Page 8 and Figure 6 as it relates to Figure S3, it is unclear from the SEM that the lithium coating SEM images were from the inside the droplet morphology or outside it. Can the authors clarify this? What is the morphology of lithium in both parts? Is it still porous inside and outside the droplet area?
Further for the tested cells, was the lithium taken from inside the droplet area or was it prepared in a different way on smaller cut pieces of Cu foil?
can the authors also comment on how different would the electrochemical performance be for a cell made from lithium within the droplet morphology versus outside it.
- Figure 8, can the authors label the different colored curves? Do they represent different conditions? different batteries?
- From Figure 7, comparing the electrochemical results from the different conditions can help provide a better understanding on the influence of the porous lithium on battery performance. Can the authors add these results to Figure 8?
- Section 3.3 - it would be worthwhile to rewrite this section to focus on the most important challenge.
- Section 4.4 is recommended to also be rewritten in accordance with the introduction and change in focus for the manuscript
- Section 4.5 and associated upscaling figures should be omitted. Given the work in the manuscript , the upscaling potential is merely conjecture at this point and does not provide any relevance. At the industrial scale major challenges occur and even the research challenges have not been fully resolved to even entertain this discussion.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
After careful review of the author's response and the revised manuscript,
the authors fail to sufficiently address the reviewer's comments.
Specifically the following points:
- Point 1 (Overall, the reviewer recommends the focus of the manuscript to be changed towards lithium deposition and the influence of pre treatment on the lithium morphology. Porous lithiated silicon and associated advantages as mentioned in the introduction led to delamination issues and hence should be presented briefly, if at all, with only 1 figure as applicability of the proposed PVD technology to other systems and that more work is needed to address issues with silicon. - Section 3.3 - it would be worthwhile to rewrite this section to focus on the most important challenge. - Section 4.4 is recommended to also be rewritten in accordance with the introduction and change in focus for the manuscript)
- A discussion of current challenges are always welcome and is a part of research as well as contradicting results. However, the adhesion of the lithium silicon film is an incomplete optimization that is presented in as-is format due to time limitations (Page 11 Line 360) and cannot be associated with a challenge that the field is facing. Further, the discussion on Li-Si is continued throughout the manuscript and in Points 2 and 7 of the reviewer comments.
Point 6 (From Figure 7, comparing the electrochemical results from the different conditions can help provide a better understanding on the influence of the porous lithium on battery performance. Can the authors add these results to Figure 8?)
- Figure 7 shows the SEM results without any plasma pre-treatment and adding the results from untreated samples would bring out the benefit of the treatment, however the authors fail to add this to Figure 8.
Author Response
Please see the attachment.
In our stage 2 response, we used the former response file, insert the new reviewer comments in blue, and added our answer below.
Author Response File: Author Response.docx
Round 3
Reviewer 3 Report
The reviewer would like to thank the authors for another submission of the manuscript for consideration.
My apologies for the late response on account of my health.
The decision still stands at rejecting the manuscript. The comments at the last round have not been sufficiently addressed.
Overall, the reviewer would like to thank the authors for all the hard work of putting together this manuscript and the experiments itself. The work on porous lithium is novel and I would strongly recommend to publish it if the manuscript focus was only on the porous lithium work.
However the concerns around lithiated silicon have not been sufficiently addressed either in the reviewer response or the manuscript by way of additional references, images, data or otherwise. As such its difficult to accept the manuscript in current form and is recommended to be rejected.
Author Response
The authors wish the reviewer all the best for the New Year 2023, as well as happiness, success for the scientific work and above all health. We thank you for another review and appreciate that you sacrificed parts of the Christmas holidays for the report.
We appreciate that the reviewer considers the approach for porous Li layers as innovative. Nevertheless, the authors are sorry that they could not convince the reviewer of the Li-Si approach by their multiple revisions and by arguments in their response. However, we respect the reviewer's decision and in a certain kind, we can understand the steadfast adherence to his attitude.
Nevertheless, the authors remain convinced that the results obtained for Li-Si approach have reached an intermediate state that is worthy of being presented to the scientific community by a publication. Therefore, we prefer to publish the current multiple revised version.
We perceive that currently a stalemate is achieved and the dissent cannot be surmounted by bilateral communication. Therefore, considering mediation by a neutral person would be appropriate at the current time. Hence, we have written a letter to the academic editors and asked for their assessment.
We hope that the reviewer will also be able to respect our attitude and will not refuse to further collegial exchange.
Sincerely,
The Autors
Author Response File: Author Response.docx
