Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Hybrid electrolytes, which rationally integrate the benefits of single inorganic solid electrolytes and solid polymer electrolytes as well as achieve sufficiently high ionic conductivity, low interfacial impedance, and high electrode stability, have attracted significant interest for use in SSLBs.

The manuscript presents the synthesis and properties of a set of hybrid polymer electrolytes (HPEs), comprising incorporated silica in the network. The HPEs were characterized by FTIR, DSC, EIS and their electrochemical performance was explored by assembling electrolytes in LCO, NMC(811), and LFP coin half-cells. The authors declare that such a type of electrolyte with high safety and good electrochemical performance provides a potential approach for developing a safer lithium-ion battery.

The paper is well-structured and relevant for the field; the experimental data seem to be reliable. Unfortunately, not all results are interpreted appropriately and not all statements are supported by the results.

The following principle points should be mentioned concerning the manuscript content and data presentation: 

1             Figure 2:

-          Caption should be corrected: (b) is used twice; (d) is absents;  the meaning of HPE is not explained. Is HPE = HPEf0?

-          It is desirable to improve the quality of the figure (plots)

2             The meaning of Tg* is not explained (Table 1)

3             The description of “Thermal characterization of hybrid polymer electrolyte HPEf “(3.1.2) is unsatisfactory. In fact, the text (section 3.1.2) and Figure 3 provides no evidence for the existence of either Tg / Tg* (Table 1), or “complex behavior” (line 220). “The eutectic mixture has a noticeable melting transition during the second heating scan” (lines 213, 214) – there is no data on the second heating run. The speculations about eutectic mixtures, bi-phase nature of the hybrid electrolyte are baseless. It is difficult to agree that DSC results “…offer important information about modifying hybrid electrolyte…” (line 223).

To improve the quality of data presentation and discussion it is desirable:

-          to give Tm values and Tg/Tg* transitions  in the Figure 3;

-          to rearrange lines in Table 1. (PEO - HPE(???) - HPEf5- HPEf10 HPEf15 HPEf20).

-          It is necessary to show glass transition (Tg and Tg*) in DSC curves and “noticeable melting transition” in second heating run. 

It seems that the DSC data are not vital for the discussion and, therefore, the assumptions about eutectic mixtures and multiphase character of HPEfs can be omitted. In any case, part 3.1.2 should be carefully modified according to the DSC results; the hypotheses should be discussed/illustrated using relevant references.       

3             Additionally, in Conclusion section it is highly desirable to specify the novelty of the results and advantages of the approach compared to known analogues.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

 

In this paper the Authors show hybrid polymer electrolytes, comprising different wt% of incorporated silica in the network that were synthesized and subjected to analysis. FTIR studies confirmed the intricate interactions among silica, the polymer salt. The examination extended to determining transference numbers, encompassing a temperature range from 25 to 70°C with intervals of 15°C. HPEf15 electrolyte, which exhibited a promising initial discharge capacity of 143 mA/g for NMC(811) at 0.1 C, 134 mA/g for LCO, and 139 mA/g for LFP half-cells, all at 0.1 C and 55°C. They show that the results from half-cells featuring the hybrid polymer electrolytes, a Li metal anode, and a LiFePO4 cathode were particularly encouraging.

 

The description of the work is acceptable. Overall impression is that this manuscript can be recommended for publication after MINOR revision in Sustainability especially considering the scope and topics of this journal. However, I would like to point out to several details:

 

1. Do the Author have optimization of the scan rate experiments, because they choose 0.1 mV s⁻¹? Explain this.
2. Do the Authors have any other hybrid polymer electrolyte characterization except FTIR and thermal characterization? Explain this.
3. The authors should avoid vertical rules in the tables. Correct this.
4. Figure 5. should include error bars. Correct this.
5. Please make sure your conclusions' section underscore the scientific value added of your paper, and/or the applicability of your findings/results. Highlight the novelty of your study. Clearly discuss what the previous studies that you are referring to are. What are the Research Gaps/Contributions.
6. English language should be corrected by a professional lector. A proof reading by a native English speaker should be conducted to improve both language and organization quality.

I wish a lot of success to the authors in making this manuscript better.

With kind regards!

Reviewer 

 

Comments on the Quality of English Language

1. English language should be corrected by a professional lector. A proof reading by a native English speaker should be conducted to improve both language and organization quality.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

1. The selective choice of abbreviation is absolutely unclear particularly in the abstract. It is better to use abbreviations at the first mention of the subject (e.g., LFP, LCO, PEO and so on).

 

2. What exactly is the novelty of this research? It should be more clearly emphasized the advantage of the as-prepared batteries compared to the well-known ones of the same type.

 

3. XºC (lines 22, 26, 26).

 

4. How did the dear authors prove greater safety of the lithium-ion battery obtained (line 28).

 

5. How do the dear authors explain the non-linearity of the sigma with an increase in HPEf content (Table 2)?

Comments on the Quality of English Language

As far as I can see, English is quite comprehensive.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors made necessary correction and the manuscript can be recommended for publication.

Nevertheless, it should be pointed out that the revisions made to Section 3.1.2 did not change the Section substantially. The DSC curves (Figure SII) shows that endothermic steps ascribed to glass transition are weakly expressed, especially for PEG. The presence of two distinct glass transition temperatures in the case of HPEf5 is not obvious. The glass transition is observed as a small variation in the baseline of the measurement curve and qualitative data (an onset, a midpoint; delta Cp) can hardly be determined from the presented curves (compare, for example.,  ref [26]).

Therefore, the experimental DSC data do not give reliable basis for reasoned assumptions about “…complex behavior”, “…intricate interplay between silica and PEO”, “the presence of two distinct phases within the hybrid electrolyte”. It is up to authors to include this data in the paper. The DSC results are not used for discussion and do not influence conclusion. I would recommend minimizing speculations on DSC results (optional)

Author Response

• The authors made necessary correction and the manuscript can be recommended for publication.

Answer: We would like to appreciate your kind response. We did our best to contribute our study to the Sustainability journal. 

• Nevertheless, it should be pointed out that the revisions made to Section 3.1.2 did not change the Section substantially. The DSC curves (Figure SII) shows that endothermic steps ascribed to glass transition are weakly expressed, especially for PEG. The presence of two distinct glass transition temperatures in the case of HPEf5 is not obvious. The glass transition is observed as a small variation in the baseline of the measurement curve and qualitative data (an onset, a midpoint; delta Cp) can hardly be determined from the presented curves (compare, for example.,  ref [26]).

Answer: We would like to thank the reviewer's comments. The glass transition temperature obtained from our study indicates the onset of molecular mobility; below this temperature, molecular movement ceases, rendering the elastomer rigid and glass-like. Its property depends on the molecular weight and properties of the matrix polymers and the reinforcement within it. Additionally, the data directly obtained indicates the T_g slope. We conducted our experiment diligently, ensuring our data's accuracy and avoiding fraudulent practices.

The sustainability of this electrolyte is evident in its performance after 100 cycles at 55°C. Given the duration of each battery cycle, the cell exhibits prolonged functionality while maintaining significant retention consistently. This underscores the sustainable nature of our materials in practical application.

• Therefore, the experimental DSC data do not give reliable basis for reasoned assumptions about “…complex behavior”, “…intricate interplay between silica and PEO”, “the presence of two distinct phases within the hybrid electrolyte”. It is up to authors to include this data in the paper. The DSC results are not used for discussion and do not influence conclusion. I would recommend minimizing speculations on DSC results (optional).

Answer: Thank you for your suggestion. Nonetheless, we have included all the data we obtained in both the manuscript and supplementary information. Please understand that not all the equipment used in our study is owned by our group, necessitating us to send materials to another center for further testing. Whenever we receive results from our colleagues, we strive to provide comprehensive explanations. We kindly request your understanding regarding this situation.