Recycling Positive Electrode Materials of Li-Ion Batteries by Creating a pH Gradient Within Aqueous Sodium Chloride Electrolyser

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I read the manuscript titled “Recycling Positive Electrode Materials of Li-ion Batteries by Creating a pH Gradient within Aqueous Sodium Chloride Electrolyser” submitted to the Processes. This work presents a well-structured and innovative approach to the recovery of cathode materials from lithium-ion batteries. The study introduces a novel proof-of-concept strategy involving the electrolysis of an aqueous NaCl solution, with the generated HCl directed to the anode chamber to aid in the recovery process. The manuscript is generally well-written and it includes novel approaches in terms of Li-ion battery material recovery. In addition, the results are supported by different characterization techniques such as XRD, SEM, and XPS.

Overall, the manuscript is well-written, provides significant insights, and makes a valuable contribution to the literature. I believe it is suitable for publication in its current form.

Minor Suggestion: It would be beneficial to emphasize the novelty of the proposed method more clearly in the Introduction section, to better highlight the study’s contribution to the field.

Author Response

please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

1. The abstract is a bit too dense. Consider simplifying some technical parts and moving detailed data (e.g., 98.8% Li) to the main results section.
2. The manuscript mentions the generation of HCl from H₂ and Cl₂ but does not detail the mechanism of how this reaction occurs within the system. Clarifying this reaction pathway is crucial for reproducibility.
3. The authors should provide direct experimental evidence (e.g., titration, spectroscopy) confirming the in-situ formation of HCl from electrolysis products.
4. The manuscript should include detailed chemical analysis (e.g., XRD, FTIR, SEM-EDS) of the precipitates formed in the cathode chamber to identify recovered species.
5. Please provide data or discussion on the longevity and degradation resistance of the dimensionally stable anode (DSA) used during extended electrolysis.
6. The novelty of the proposed technique would be strengthened by including a performance comparison with conventional acid leaching or hydrometallurgical methods.
7. The authors should include stoichiometric analysis of the overall chlorine cycle and quantify any possible losses during the reaction steps.
8. A basic energy efficiency or consumption analysis (e.g., Wh/g of metal recovered) would greatly strengthen the case for industrial application.
9. The feasibility of scaling up the process should be addressed. Are there any anticipated challenges (e.g., gas management, corrosion, safety)?
10. If the process aims to reduce wastewater, please include data on the composition of the final liquid waste from both chambers.
11. The stability of the pH gradient throughout the electrolysis should be discussed. Was there any need for pH adjustment during the 13.5 hours?
12. Expand slightly on how this method supports green chemistry principles, e.g., reducing secondary pollution, energy input, etc.
13. The conclusion should emphasize the practical relevance of the results and how the system might be adapted for industrial-scale battery recycling.

Author Response

please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

All comments are gathered in the attached file

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Satisfied