Graphyne Nanotubes as Promising Sodium-Ion Battery Anodes
and Jin Yong Lee 2,*Round 1
Reviewer 1 Report
The manuscript deals with extensive calculations of graphyne nanotubes as potential candidates for sodium-ion batteries.
The introduction part sufficiently covers existing literature. The following computational method part is brief, refering to the supplementary material for optimized structures. Maybe authors can mention if spin-polarization was applied in their calculations.
Results are deeply discussed in three parts - single Na adsorption on GyNTs, sodium storage capacity of GyNTs and sodium diffusion and migration on GyNTs.
Via calculations, authors reported material with the largest Na storage capacity, that is the (3,0)-alphaGyNT system. Together with betaGyNT are promising candidates for SIB anodes.
Two minor isseus. Formula 2: Fix placing the comma after the formula, not after the characted in the denominator, it looks like e´ . Line 125: please remove the "\" characted from before Ebcc-Na.
Author Response
Comment: The manuscript deals with extensive calculations of graphyne nanotubes as potential candidates for sodium-ion batteries.
The introduction part sufficiently covers existing literature. The following computational method part is brief, refering to the supplementary material for optimized structures. Maybe authors can mention if spin-polarization was applied in their calculations. Results are deeply discussed in three parts - single Na adsorption on GyNTs, sodium storage capacity of GyNTs and sodium diffusion and migration on GyNTs. Via calculations, authors reported material with the largest Na storage capacity, that is the (3,0)-alphaGyNT system. Together with betaGyNT are promising candidates for SIB anodes.
Response: Actually, all the calculations were performed with spin polarization which was mentioned in the revised MS (Lines 106-107).
(1) Two minor issues. Formula 2: Fix placing the comma after the formula, not after the characted in the denominator, it looks like e´. Line 125: please remove the "\" characted from before Ebcc-Na.
Response: Typos about formula were corrected and removed “\” following reviewer’s comment in the revised MS. (Lines 122 and 128)
Reviewer 2 Report
It is very important to develop high-performance anode materials for sodium-ion batteries. Compared with carbon-based materials, the authors explored graphyne nanotubes, which show superior performance. This work presented excellent theoretical study of the property of graphyne nanotubes, and the findings are of high novelty. Some minor commments are recommended to be addressed.
1, Compared with carbon-based materials, the synthesis of graphyne nanotubes will be much more difficult. Therefore, the authors should clarify it in the manuscript.
2, It is recommended to study the Na storage property of carbon nanotubes as well, which is similar to the structure of graphyne nanotubes.
3, Since it is difficult, or even impossible to synthesis graphyne nanotubes experimentally, the authors should provide some general ideas for the study of graphyne nanotubes. For example, such design principles of carbon-based materials to improve their Na storage properties.
Author Response
Reply to Reviewer 2
Comment: It is very important to develop high-performance anode materials for sodium-ion batteries. Compared with carbon-based materials, the authors explored graphyne nanotubes, which show superior performance. This work presented excellent theoretical study of the property of graphyne nanotubes, and the findings are of high novelty. Some minor commments are recommended to be addressed.
(1) Compared with carbon-based materials, the synthesis of graphyne nanotubes will be much more difficult. Therefore, the authors should clarify it in the manuscript.
Response: It is correct that the synthesis of graphyne nanotubes is difficult when compared to other carbon materials. However, great progress has be made in the field of synthesizing graphyne materials. Since the first experimental synthesis of graphdiyne, many different graphyne materials have been reported one by one with different method, like γ-graphdiyne by chemical method of template coupling, β-graphdiyne by wet chemical method, γ-graphyne by mechanochemical method, N-graphyne by ball-milling synthesis, and so on. Furthermore, researchers are devoting to develop low dimensional graphyne materials in recent years. In 2011, multi-walled graphdiyne nanotubes were synthesized successfully by Cu-surface-mediated synthesis. Recently, graphyne nanoribbons have been synthesized as well, indicating that the technique of synthesizing graphyne have been becoming more and more matured. So, we strongly believe that the materializing graphyne nanotube would be expected in the near future. (Lines 90-92)
(2) It is recommended to study the Na storage property of carbon nanotubes as well, which is similar to the structure of graphyne nanotubes.
Response: Following reviewer’s comment, we studied the Na adsorption on (5, 5)-CNT, whose radius in similar the (3, 0)-αGyNT possessing the largest capacity. Result shows that the bind energy of single Na on CNT is -0.58 eV which larger than cohesive energy of bulk Na (-1.04 eV), indicating pristine CNTs cannot be sodium-ion battery anodes. Such weak interaction between Na and CTS could be ascribed to the smaller specific surface and holes that cannot stably anchor a Na atom, when compared to graphyne nanotubes.
(3) Since it is difficult, or even impossible to synthesis graphyne nanotubes experimentally, the authors should provide some general ideas for the study of graphyne nanotubes. For example, such design principles of carbon-based materials to improve their Na storage properties.
Response: It is a good comment that can make our paper more readable for wider audiences. Though it is difficult to synthesize GyNTs, our findings still provide some ideas for designing SIB’s anode materials as stated in the conclusion. The first one is to increase the specific surface area, and to have uniformly located pores with enough size to anchor Na like alpha-graphyne. The second one is that manipulating the electronic properties via tension or rolling into nanotube is necessary to enhance their interactions with Na atoms.
