Two Promising Methodologies for Dealing with Changes in Optical and Electrical Properties of Polymer Electrolytes (SPEs)

Round 1

Reviewer 1 Report

This paper reported the characterizations of optical properties of polymers, such as infrared dichroism, optical absorption, Raman polarization, and emission spectra, were used for investigating electronic properties. Based on my review I recommend the publication of this manuscript after a revision. Below I am adding my comments.

1.     Introduction- “…… For example, it should be a polar polymer with a low barrier to bond rotation and a high electron-donating capacity suitable for forming coordination with cations……”. The authors should state the purpose of this work rather than just introduce the advantages of the material.

2.     Abstract: “To calculate the electrical conductivity and provide heat in the range (of 300-500 K), we also investigated the effect of temperature on the electrical conductivity. Activation energies found in different conditions were used”, The authors should give the research results in details.

3.     “The thin films' optical energy gap (Eg) has been determined from absorption coefficient data as a function of photon energy”. Can the authors supple the Eg values?

4.     “It is found that with decreasing AsF₆ concentration, there is a shift in the band edge and a change in the slope of the absorption spectra, as shown in Figure 4”. What kind of change is it? The authors should describe this change and explain clearly.

5.     “Figure 6 represents the temperature dependence of ionic conductivity for all compositions of S.P.E.s.”. Why did the author choose the temperature range of 300-500 K?

6.     It is better to summarize the optical and electrical properties of polymer electrolytes in this work and other reports for comparison.

Author Response

This paper reported the characterizations of optical properties of polymers, such as infrared dichroism, optical absorption, Raman polarization, and emission spectra, were used for investigating electronic properties. Based on my review I recommend the publication of this manuscript after a revision. Below I am adding my comments.

 

1. Introduction- “…… For example, it should be a polar polymer with a low barrier to bond rotation and a high electron-donating capacity suitable for forming coordination with cations……”. The authors should state the purpose of this work rather than just introduce the advantages of the material.

Changes in optical absorption, principally changes and absorption edge shape, are two promising methodologies that seek to understand the fundamental processes of optical transitions in crystalline and amorphous materials. This allows us to better understand the structure of the energy bands. Significant progress has been made in understanding the basic chemical and physical properties of polymers in order to increase the efficiency of photovoltaic and optoelectronic devices. However, a relationship between these two properties has not yet been established. Characterization of the optical properties of polymers, such as infrared dichroism, optical absorption, Raman polarization, and emission spectra, is an important approach for examining electronic properties. In order to account for electrical conductivity and heat savings in the range (300–500 K), we also investigated the effect of temperature on electrical conductivity. The activation energies found in different circumstances were used. It was found that temperature dependence of ionic conductivity for all SPE formulations. It is found that the ionic conductivity of the membranes exhibits two regions, the first being at a relatively low temperature. The ionic conductivity exhibits a behavior that is relatively temperature-independent. It is found that the dielectric constant increases with increasing temperature for the SPE polymer electrolyte system. This behavior is typical of polar insulators, as the alignment of dipoles becomes easier with increasing temperature and thus the permittivity increases. It is evident from the graphs that the dielectric constant monotonically decreases with increasing frequency and reaches a constant value at higher frequencies.

In this way the purpose of this work was established rather than simply presenting the merits of the article.

 

2. Abstract: “To calculate the electrical conductivity and provide heat in the range (of 300-500 K), we also investigated the effect of temperature on the electrical conductivity. Activation energies found in different conditions were used”, The authors should give the research results in details.

The results of the research were given in detail as requested by the reviewer.

 

3. “The thin films' optical energy gap (Eg) has been determined from absorption coefficient data as a function of photon energy”. Can the authors supple the Eg values?

From figure (4), the energy gap can be calculated and found to range from 4.7 into 5.2 e.V

4. 4. “It is found that with decreasing AsF6 concentration, there is a shift in the band edge and a change in the slope of the absorption spectra, as shown in Figure 4”. What kind of change is it? The authors should describe this change and explain clearly.

AsF6– has forth eight valence electrons, out of which twelve are bonding electrons, and the remaining thirty-six are non-bonding electrons present on six fluorine atom. The twelve bonding electrons are distributed between the six arsenic and fluorine covalent bonds. Six non-bonding electrons or three lone pairs are present on each fluorine atoms. According to VSEPR theory, the central atom is As, which forms covalent bonds with six fluorine atoms, with the molecular and electron geometry being octahedral. The six fluorine atoms are symmetrically arranged around the central atom arsenic along the vertices of an octahedron. Here all the atoms around the central atom are the same, so a regular octahedral geometry is formed(when different atoms surround the central atom, in this case, there can be a distortion in geometry, also known as the Jahn-Teller effect). According to VSEPR theory, the electron density(bond pairs, lone pairs, and electrons of multiple bonds) is arranged to minimize repulsions by being as far apart as possible. The shape of an AX6 type molecule with six bonded atoms and zero lone pairs is octahedral.

This change in optical band gap may be discussed on the basis of the change in average bond energy as a function of composition. Since optical band gap is a bond sensitive property, a decrease in the average bond energy results in a decrease in the optical band gap

According to the chemical – bond approach which assumes that, bonds are formed in sequence of decreasing bond energies until all available valences for the atoms are saturated.

5. “Figure 6 represents the temperature dependence of ionic conductivity for all compositions of S.P.E.s.”. Why did the author choose the temperature range of 300-500 K?

Thermogravimetric analysis (TGA) curves for both polymers showed a slight decrease in weight loss percentage starting from 300 K to around 500 K; After that, weight loss increases at rates above about 500 K.

 

6. It is better to summarize the optical and electrical properties of polymer electrolytes in this work and other reports for comparison.

These characteristics were exposed through the results and conclusion.

Author Response File: Author Response.docx

Reviewer 2 Report

1) Experimental part needs to be detailed

Please describe how ionic inorganic salts are dissolved in coordinated polar polymeric hosts. the description of LiX (where X = 1 [pure], Br, CF3SO3, BF4, AsF6) is confusing. Please clarify what X=1[pure] means. What is the molecular weight of PEO and PPO? Is dry SPE made with pure PEO or PPO or the mixture of PEO and PPO? If it is the mixture, what is the ratio of PEO/PPO. Please provide how the conductivity was measured at different temperatures. Is temperature hold constant or keep changing at 2K/min?

 

 1) The dry solid polymer electrolyte P.E.O. interacts with Li+ salts and is shown in Figure 1. –CH2–CH2–O– and the presence of polar groups. Please clarify what you want to say here.

2) The conductivity of pure S.P.E.s is equal to ≈5x10-4 S cm-1 and increases sharply to ≈2.1x10-3 S cm-1, and when doping with AsF6 the conductivity becomes ≈ 7x10-4 S cm-1 and strongly increases a ≈ 2.4x10-3 S cm-1 .

This is confusing. Please clarify

Author Response

Reviewer 2

1) Experimental part needs to be detailed

 

Please describe how ionic inorganic salts are dissolved in coordinated polar polymeric hosts. the description of LiX (where X = 1 [pure], Br, CF3SO3, BF4, AsF6) is confusing. Please clarify what X=1[pure] means. What is the molecular weight of PEO and PPO? Is dry SPE made with pure PEO or PPO or the mixture of PEO and PPO? If it is the mixture, what is the ratio of PEO/PPO. Please provide how the conductivity was measured at different temperatures. Is temperature hold constant or keep changing at 2K/min?

A solid polymer electrolyte (SPE) is defined as a solvent-free system with the ionic conducting phase formed by dissolved salts in a polar polymer matrix. SPEs have three important functions in polymer electrolyte batteries: (i) they carry cations (mostly lithium ions); (ii) they work as an electrode spacer eliminating the need to incorporate an insert porous separator, and (iii) SPEs can provide good electrical contact with electrodes, which means they do not need to be in the liquid phase

The polymer contain atoms or groups with sufficient electron donor power to form co-ordination bonds with cations. For alkali ions, such as lithium, oxygen is regarded as the preferred electron donor, polymer have a suitable distance between coordinating sites to allow the formation of multiple intra-polymer bonds for good solubility of cations.  The polymer have low barriers to bond rotation to facilitate ion motion Potential candidates for a polymer host are : poly (methylene oxide) (-CH₂O-)n , poly (ethylene oxide) (-CH₂CH₂O-) n, poly (trimethylene oxide) (-CH₂CH₂CH₂O-) n, poly (propylene oxide) (-CH₂CH₂(CH₃)O-)n , and poly (ethylene imine) (-CH₂CH₂NH-)m.

 The first of these, poly (methylene oxide), – (CH₂-O) n, has a relatively rigid chain , while the third, poly (trimethylene oxide), – (CH₂-CH₂-CH₂-O) m , is unable to adopt low-energy conformations.  PPO is the second most extensively used polymer in polymer electrolyte studies after PEO. Unlike PEO which has coexisting amorphous and crystalline phases, PPO is completely amorphous. However, at higher temperature, e.g., higher than 60-80^oC, PPO/salt systems display appreciably lower conductivities than those measured under the same conditions for PEO/salt complexes, caused by the steric hindrance from the pendant methyl group.

 Finally PEI is a product of the cationic polymerization of the ethyleneimine or the cationic ring-opening polymerization of aziridene. It is highly hygroscopic and, unlike PEO or PPO, can also form hydrogen bonds (N-H…N) between polymer chains. In anhydrous state, these hydrogen bonds lead to the formation of double-stranded helical chains, which can decrease the ionic conductivity.

 As a result, neither of them can be used as polymer electrolytes, with most SPEs being based on the commercially available polyethylene oxide (PEO) polymer. PEO has very good solvating properties for a wide variety of salts, due to the interaction of its ether oxygen with cations. The chemical structure of PEO explains most of the properties of this polymer host.

 

 The melting point of PEO is a function of the average molecular weight and molecular weight distribution of the sample. Usually, it varies from 60oC for lower molecular weights (~4000 g/mol) to 66oC for bigger molecular weights (~100,000g/mol). The glass transition temperature (Tg) also displays a close relationship with molecular weight, it grows up to a value of -17^oC of a molecular weight 6000g/mol. Values of -65 and -60^oC are reported for

higher molecular weight samples. PEO is completely soluble at room temperature in water and also soluble in a wide range of common organic solvents . PEO and most PEO/salt mixtures exhibit co-existence between crystalline and amorphous phases; in fact only 15-30% of PEO is in the amorphous phase at room temperature .

The bulk sample, which used in the conductivity measurements, was prepared by splitting the crystal along the cleavage plane andhence the resultant surface was mirror-like without any mechanical treatment. Then it was mounted on the coldfinger inside a cryostat (Oxford DN1704-type), which was evacuated to about 10^-4torr. The temperature insidethe cryostat was controlled by a digital temperature controller (Oxford ITC601-type). The contacts between the samples and the metal electrodes were made by using silver paste. The electrical contacts have been tested to analyze their I-V characteristics and are found to be Ohmic in the used range of the applied voltage. conductivity measurements have been carried out by both pulsed excitation (a.c) and steady state (a.c) methods. The temperature hold is constant.

 

Comments on the Quality of English Language

 1) The dry solid polymer electrolyte P.E.O. interacts with Li+ salts and is shown in Figure 1. –CH2–CH2–O– and the presence of polar groups. Please clarify what you want to say here.

Polymer electrolytes have also been considered to improve the performance of Li batteries due to the excellent properties regarding ion transport similar to those of non-aqueous liquid electrolysis systems. The low leakage potential, consumable flammability, and large energy density have generated interest in polymer electrolytes over conventional formulations. Polymer electrolytes generally consist of Li-based salts mixed with polyether solvents. The major classification of polymer electrolytes includes polymer gel electrolytes and complex polymer electrolytes (CPEs). It has been reported that polymeric electrolytes have the ability to act not only as electrolytes but also as submarines and prevent the generation of dendrites, PS solubility problems and safety issues. Due to the chemical stability. The lithium salt acts in electrolytes in which the maximum conductivity has been reached and the maximum conductivity has been achieved. While CH₂-CH₂-O is currently the most widely used in mixed carbonate solvents. It has also been shown that for electrolytes with CH₂-CH₂-O in solvent mixtures, the conductivity is significantly higher.

 

2) The conductivity of pure S.P.E.s is equal to ≈5x10^-4 S cm^-1 and increases sharply to ≈2.1x10^-3 S cm^-1, and when doping with AsF6 the conductivity becomes ≈ 7x10^-4 S cm^-1 and strongly increases a ≈ 2.4x10^-3 S cm^-1 .

This is confusing. Please clarify

polymers with successive structures have semiconductor properties.  containing an extension of electrons along the polymeric chain. where the electrical conductivity values of semiconductors range between (10^-4–10^-3) S.cm^-1, and it is much larger than insulating materials and lesser than metals. we have focused on successive polymers in their quest to develop polymers with high electrical conductivity characteristics, The prevailing belief was that the delocalization of electrons that is supposed to happen in these polymers is necessary to give a high concentration of charge carriers that carry the current, but the

scientific results clearly showed that the delocalization of electrons along the chain is not sufficient to make these polymers have high conductivity where they are at best weak semiconductors, this is because the electron transfer process takes place within a single chain, meaning that the electronic sequence is cut off at the end of the chains, but charges that have mobility can be generated, either by shining light, shedding an electric voltage, or introducing chemicals called dopants and by the process of doping, which has a great role in giving off a high concentration of charge carriers that transmit electric current.

There are many studies that have been concerned with the electrical properties of polymers and the effect of monomeric doping of various kinds on them. Polyaniline is one of the family of successive polymers. and it is semi-flexible rod polymer, and it has a number of important properties and applications.

 

 

 

 

 

 

 

 

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

Recommendation: Reconsider after major revision

 

The manuscript “Two promising methodologies for dealing with changes in optical and electrical properties of polymer electrolytes” aims to provide insight on the effect of lithium counter ions on the optical and electrical properties of the polyethylene oxide (PEO) electrolyte. The authors utilized NIR-UV-Vis spectroscopy to examine absorbance of various PEO electrolytes doped with different lithium salts. The optical results were analyzed with various equations to give optical and electrical properties such as refractive index, absorption coefficient, conductivity, and dielectric constant. Different temperatures were also applied to investigate the temperature-dependence of these properties.

 

Major comments:

1. The authors did not specify the reasons of choosing these different lithium salts. More importantly, comprehensive explanation on why these various salts acted differently was missing. The authors described most of the experimental results but did not provide in-depth discussion. It would be helpful to learn what different kinds of interactions these counter ions had with PEO matrix. Was the difference caused by size difference, polarity, H-bonding, or something else? These are type of questions that the authors need to address.

2. Some key experimental details are missing. For example, the authors hypothesized that the degree of crystallinity was one of the reasons of changing conductivity with different salts. However, no data on crystallinity determination was provided. X-ray scattering/diffraction, SEM/TEM, DSC, polarized optical microscopy etc., could be helpful sources to determine such conclusion (also easy to operate). Another example is how did the author measure thickness and resistance of the spin-coat film? It is not as trivial as it sounds. Several different techniques are required for such measurements.

3. The authors stated several times that the optical properties were changing with doping concentration (amount); however, it is not clear what the doping concentration is and none of the figures showed a correlation with doping amount (except Figure 5). It can cause confusion for readers. Most of the results only showed different types of salts, not different concentrations.

4. Since the manuscript was submitted to Journal of Composite Science, the authors need to emphasize the correlation with composite. Typically, polymer electrolyte is not considered as polymer composite because the latter is usually a combination of polymer matrix and particulate fillers. One example is graphene-reinforced polymer. The authors should illustrate why such system can be regarded as composite and what can this study suggest to the composite field. 

 

Minor comments:

1. In Figure 1. Why the absorbance is not zero for non-absorbing area and why the absorbances of different samples at this range (i.e., the baseline absorbance) are not the same.

2. What does the change of slope in Figure 4 suggest in terms of different counter ions?

3. Symbol “A” was used as both area and absorbance in the manuscript.

4. A noticeable number of typos and grammar mistakes were present.

The overall quality of English was acceptable. However, a number of typos and grammar mistakes were present. Please revise the language and consider seeking support if needed. 

Author Response

Reviewer 3

Recommendation: Reconsider after major revision 

The manuscript “Two promising methodologies for dealing with changes in optical and electrical properties of polymer electrolytes” aims to provide insight on the effect of lithium counter ions on the optical and electrical properties of the polyethylene oxide (PEO) electrolyte. The authors utilized NIR-UV-Vis spectroscopy to examine absorbance of various PEO electrolytes doped with different lithium salts. The optical results were analyzed with various equations to give optical and electrical properties such as refractive index, absorption coefficient, conductivity, and dielectric constant. Different temperatures were also applied to investigate the temperature-dependence of these properties. 

Major comments:

The authors did not specify the reasons of choosing these different lithium salts. More importantly, comprehensive explanation on why these various salts acted differently was missing. The authors described most of the experimental results but did not provide in-depth discussion. It would be helpful to learn what different kinds of interactions these counter ions had with PEO matrix. Was the difference caused by size difference, polarity, H-bonding, or something else? These are type of questions that the authors need to address.

In this work, I used surface modified materials, which possess a surface bound by polyethylene oxide (PEO) chains, and tested their adhesion in epoxy, vinyl ester, and polycarbonate. A unique opportunity to check their adhesion in a range of polymers and adhesion. Importantly, PEO polymers have been shown to be miscible in a variety of polymers, including mixtures with polyamide polycarbonates and polystyrene. Furthermore, PEO groups are miscible in epoxy and, when used in chelation of metal ions, have been shown to improve curing. It is important to note that the ratio of PEO groups to the polymer matrix is extremely high in this investigation, localizing entirely to the interface. They are covalently bound to the surface of the fiber, although it is capable of stretching and interlocking with the supporting polymer matrix, especially at elevated curing temperatures.

Increased polarity of non-polar polymers indicating surface attachment. Polarity and adhesion were not the full picture. General oxidation techniques used to increase the oxygen content on the surface of the fiber, usually a combination of functional groups is presented. Bottom surface modified with PEO polymers that have a very high oxygen content and are able to use up the particles

2. Some key experimental details are missing. For example, the authors hypothesized that the degree of crystallinity was one of the reasons of changing conductivity with different salts. However, no data on crystallinity determination was provided. X-ray scattering/diffraction, SEM/TEM, DSC, polarized optical microscopy etc., could be helpful sources to determine such conclusion (also easy to operate). Another example is how did the author measure thickness and resistance of the spin-coat film? It is not as trivial as it sounds. Several different techniques are required for such measurements.

Spin Coating Thickness Equation. In general, the thickness of a spin coated film is proportional to the inverse of the square root of spin speed as in the below equation where ω is angular velocity/spin speed and hf is final film thickness.

h= h₀/(1+4rw²/3h)h₀²t)^1/2

d h d t = − 2 K h 3 . where h₀ is the initial thickness of the coating material. Note that the final thickness of the film is affected more by the angular velocity and time than by the other factors.

 

3. The authors stated several times that the optical properties were changing with doping concentration (amount); however, it is not clear what the doping concentration is and none of the figures showed a correlation with doping amount (except Figure 5). It can cause confusion for readers. Most of the results only showed different types of salts, not different concentrations.

We have mentioned several times that the optical properties change with the doping concentration (quantity). (Figure 5) illustrates this matter, but there are other future researches that will address this matter more clearly.

4. Since the manuscript was submitted to Journal of Composite Science, the authors need to emphasize the correlation with composite. Typically, polymer electrolyte is not considered as polymer composite because the latter is usually a combination of polymer matrix and particulate fillers. One example is graphene-reinforced polymer. The authors should illustrate why such system can be regarded as composite and what can this study suggest to the composite field. 

 A polymer composite is a multiphase material in which the stiffeners are combined with a polymer matrix, resulting in synergistic mechanical properties that cannot be achieved from any component alone. Most often it is fiberglass, but sometimes it is Kevlar, carbon fiber, or polyethylene. Particle fillers are powdery materials, usually with a particle size of less than 100 micrometers, that are added to polymers to reduce cost, improve processability, and/or to modify one or more properties. A compound is perhaps best defined as a substance consisting of two or more distinct phases bonded together. See Universal Composite Materials. This distinguishes compounds from metal alloys in which the components are dissolved into each other. Solids can be divided into four categories - polymers, metals, ceramics, and carbon, which we consider a separate category because of their unique properties. We find both augmentations and matrix materials in the four categories. This gives us the ability to create an unlimited number of new material systems that have unique properties that cannot be obtained with any one homogeneous material.

Composite materials are usually classified according to the type of material used in the matrix. The four basic classes of composites are polymer matrix composites (PMCs), metal matrix composites (MMCs), ceramic matrix composites (CMCs), and carbon matrix composites (CAMCs).

Carbon and carbon compounds (CCCs) are the most important subclass of CAMCs. At this time, we consider the samples we used to be a polymer composite

Minor comments:

1.In Figure 1. Why the absorbance is not zero for non-absorbing area and why the absorbances of different samples at this range (i.e., the baseline absorbance) are not the same.

Values of absorption coefficient (α), so determined, have been plotted as a function of wavelength (λ) and presented in Figure 1. It is clearly observable from this figure that for virgin sample a strong absorption upto a wavelength followed by a considerable tailing exist

In absorbance spectroscopy (also known as absorption spectroscopy), the intensity of light absorbed by a sample is measured as a function of wavelength. This can provide important information about the electronic structure of an atom or molecule. Depending on the sample, absorbance measurements can also give you key insight into other material properties, such as sample concentration, phase changes, or composition changes.

An optical spectrometer outputs the intensity of detected light as a function of wavelength within the visible light region. When you measure absorbance, light passes through the sample, and the spectrometer detects the transmitted light. Using these transmittance measurements, you can then calculate absorbance at various wavelengths.

An absorbance of 0 at some wavelength means that no light of that particular wavelength has been absorbed. The intensities of the sample and reference beam are both the same, so the ratio Io/I is 1 and the log10 of 1 is zero.

2. What does the change of slope in Figure 4 suggest in terms of different counter ions?

The optical absorbance spectrum measured within the wavelength range of 0.5–6.5 eV is shown in figure 6. The presence of a single slope in the plot suggests that the films have direct and allowed transition. It is also well known that polymer is a direct band-gap material and the energy gap (Eg) can thus be estimated by assuming direct transition between conduction band and valance bands.

Theory of optical absorption gives the relationship between the absorption coefficients α and the photon energy hν for direct allowed transition as

(αhν)^1/2 = A(hν − Eg),

where A is a function of the index of refraction and hole/electron effective masses. The direct band gap is determined using this equation when linear portion of the (αhν)^1/2 against hν plot is extrapolated to intersect the energy axis at α = 0.

When you measure the absorption spectrum of a sample, it is important to note the wavelengths where maximum absorption occurs, as this can help you identify specific molecular properties. It is also important to always consider the strength of absorption at these wavelengths.

 

You can determine this using the molar attenuation coefficient, ε. This has also been referred to historically as the molar extinction coefficient and is also known as the molar absorptivity coefficient. It can be used if you need to calculate the electronic transitions associated with different peaks. For permitted transitions, ε > 1000 while for forbidden transitions, ε < 100.

You can solve for ε using Beer-Lambert's Law:

A = εCl

Beer-Lambert's law equation

Where A is the absorbance, c is the molar concentration of the molecule in the solution, and l is the path length through the sample (often the width of the cuvette, or overall film). You can also use this calculation to measure the concentration of a molecule in a thin film. The graphs below show the variation in absorption intensity with concentration. We can see here that this is a linear relationship, and this is indicated by the change of slope in Fig. 4 in terms of different anti-ions

3. Symbol “A” was used as both area and absorbance in the manuscript.

Symbol “A” is used absorbance.

4. A noticeable number of typos and grammar mistakes were present.

The manuscript will be reviewed by specialists to correct typos and grammatical errors.

Comments on the Quality of English Language

The overall quality of English was acceptable. However, a number of typos and grammar mistakes were present. Please revise the language and consider seeking support if needed. 

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

This article is advised to be published.

Author Response

Thanks Dear Reviewer 

Reviewer 2 Report

The author did not address the comments properly. I would not recommend its publication at this time.

For example: LiX (where X = 1 (pure), Br, CF3SO3, BF4, and AsF6). "X=1_(one)(pure)" did not make any sense. The reviewer thought that it might be a typo of "I" in "LiI". If it is "LiI", it is still dopant, and it is confusing to name it "pure".

The reviewer understood that the composition of SPE at concentration of 0M should be same in Figure 5. Please explain the difference in the conductivity.

 

Language needs to be improved

Author Response

This is due to the fact that in the laboratory steps during the preparation, we dissolved a solute with a group of elements. Different lithium salts were used to complex with PEO to produce an SPE LiX membrane (where X = 1 [pure], Br, CF3SO3, BF4, AsF6). In this research, we worked A control sample, so we fixed the ratio and considered it equal to zero mole The reviewer's comment was very excellent, so next time there will be a focus on this axis so that it will be taken into account in the next manuscript.

Reviewer 3 Report

Promising adjustment has been made by the authors to enhance the quality of the manuscript. In the revised manuscript, the authors provided adequate details for the experiments and results, and the English writing has been significantly improved. 

The only major comment I still have, which I mentioned in last version, is that the authors did not specify why choosing these Li salts and why did these counter ions behave differently. What trend are we seeing here and why? Was it due to polarity, some type of coordination with the polymer, bulkiness, or else? It is not satisfying to just present the data from these Li salts but not show in-depth discussion. The results are more than interesting, but I hope the authors can dig deeper into the data. 

Author Response

The conductivity of the PEO/Li salt system would increase significantly with the addition of Li salts. This is because Li salts dissociate into Li+ cations and anions in the PEO matrix, and the Li+ cations become mobile in the polymer. The increased concentration of mobile ions in the PEO/Li salt system would facilitate the transport of charge carriers, leading to enhanced electrical conductivity. Moreover, the PEO/Li salt system has some unique properties, including high ion conductivity, excellent stability, and low toxicity, which make it suitable for various applications, such as rechargeable batteries, fuel cells, and electrochromic devices. In summary, the addition of Li salts to PEO would increase its conductivity due to the presence of mobile ions in the system, leading to enhanced transport of charge carriers.

Round 3

Reviewer 2 Report

I would not recommend its publication before fixing the nonsense:

LiX (where X = 1 (pure), Br, CF3SO3, BF4, and AsF6)

LiX (where X = 1 (pure), Br, CF3SO3, BF4, and AsF6). LiX should be lithium salts as mentioned by the authors, so it does not make sense to have X=1(one).

Reviewer 3 Report

Thank you for addressing my comments. I believe the manuscript has met the publication standard.