Cationic Covalent Organic Framework as Separator Coating for High-Performance Lithium Selenium Disulfide Batteries

Round 1

Reviewer 1 Report

This proposal paper is a useful investigation on a hot research subject about reliable separators and efficient cathode materials for new rechargeable Li-SeS2 Batteries.
However, it is recommended to modify the (long and) puzzling title. It is recommended to
1)add the helpful (logo) word 'separator' (or even the 'composite separator') into the title, and
2)delete or modify the (unjustified) claims for 'Electrostatic Repulsion Sieving Effect'.
So, an alternative, and simple(r), proposal title, might be:
i) 'An improved Separator for High-performance Lithium Selenium Disulfide Batteries', or simply,
ii)'A new Separator for High-performance Lithium Selenium Disulfide Batteries'.

There are some (3) major notes/corrections:
1. Line102: Add the thickness: (Is it fragile?) Apart the diameter (19 mm) add the thickness, in: "19 mm in diameter.".

2. Line126: Show some graphs from EIS. The electrochemical impedance spectra (measured in the frequency range from 0.1 Hz to 100 kHz, using CHI660C electrochemical workstation) should add on values about weakly supported authors' claims for 'Electrostatic Repulsion Sieving Effect', in: "0.02, 0.03 and 0.04mV s-1. Meanwhile, the electrochemical impedance spectra were".

3. Line260:  A 'syntax' error. Modify 'it is clear that', by a proposal syntax, 'it is possible that', in: "with the capacity decay rate up to 0.098% and 0.12%. Therefore, it is clear that in terms of".


Also, there are two minor notes/corrections:
1. Line113: Add (minimal) specs for the MWCNs. Show some infos/Refs about (length, etc..., for) the multi-walled carbon nanotubes (MWCNs), in: "multi-walled carbon nanotubes (MWCNs) with the ratio of 4:1 were mixed in stainless".

2. Line133: A mistyping error. Correct 'm2 g' to be 'm2/g', in: "the BET specific surface area of 505 m2 g, which is basically consistent with that reported".

Author Response

Thank you for your kindly comments on this article. The manuscript has been revised by taking into account all the comments/questions of the reviewer. For ease of identification, the changes that have been made are highlighted in the revised manuscript. The attached file contents point by point response to each of the questions/comments of the reviewer.

Author Response File: Author Response.doc

Reviewer 2 Report

The authors explore the possibility of lithium-selenium disulfide batteries using the nitrogen-rich covalent organic framework (COF). The COF is a crystalline organic polymer with lightweight, good crystallinity, and metal-free frameworks with 2D or 3D.  Recently, functionalized- or redox-active COFs with stability and electrochemical performance have been reported. Overall this work is systematically organized with experiments. In addition, in-depth discussion is incorporated. For publication, however, the authors need to consider and address the following points.

-, The authors missed the key references in this manuscript. COF [Joule 1 (2017), 739-768], N-Li+ interaction [Energy Storage Materials 37 (2021) 315-324; Advanced Functional Materials 30 (2020) 1910538; Science and Technology of Advanced Materials 23 (2022) 169-188] are needed to consider in revised manuscript.

-, The authors obtained 505 m2/g of surface area from N2 isotherm. But it doesn’t show any mesoscopic and mesoscopic features. At least, a hysteretic behaviour should have appeared. In ref (36), a sharp uptake at P/P0< 0.05 has existed. How to obtain such a large surface area from Figure 1b?

-, Was there any wettability change after ATG-DMTZ-COF coating?

 

-, What is evidence to support a feature of N-rich COF?

Author Response

1. The references mentioned above have been cited in the revised manuscript.
2. Thanks for the reminder of the reviewer. We retested the nitrogen adsorption data and calculated the specific surface area in the revised manuscript, which is 201m²/g. It has been corrected in the revised manuscript.

3. As suggested by the reviewer, we have tested the electrolyte contact angles of blank PP separator and ATG-DMTZ-COF/PP separator. As shown in Figure S2 in the revised supporting information, the ATG-DMTZ-COF coating improves the wettability of the separator.

4. The XPS spectrum of ATG-DMTZ-COF as showed in Figure S3 can support that the COF is rich in N.

Reviewer 3 Report

This paper looks like a very preliminary studies on the effect of the MOF coating on the performance of lithium sulphide-selenie batteries. If we treat it as a short communication it can be accepted as it is. But if it bea full length paper more results shwong the effect of MOF structure on the battery performance should be presented

Author Response

Thank you for your recognition of this paper. Here, we emphasize that COF acts as  separator coating to increase the sieving effect of the separator, thus improving the cycling stability of Li-SeS2 cells. In this paper, we characterize the COF material and test the sieving effect of COF coated separator. In terms of electrochemical performance test, we tested the CV curves, cyclic stability, rate performance, and long cycle performance of batteries assembled by different separators under different currents. All these well demonstrate that the sieving effect of COF as a separator coating can make the battery have better performance. Therefore, we believe that our data are sufficient to support our conclusions.