Volume 46, Issue 4 pp. 4405-4416
RESEARCH ARTICLE

Understanding the role of lithium bonds in doped graphene nanoribbons as cathode hosts for Li-S batteries: A first-principles study

Sinthika S

Corresponding Author

Sinthika S

Department of Physics and Research Centre, Lady Doak College, Madurai, Tamil Nadu, India

Correspondence

Sinthika S, Department of Physics and Research Centre, Lady Doak College, Madurai 625002, Tamil Nadu, India.

Email: [email protected]

Ranjit Thapa, Department of Physics, SRM University—AP, Amaravati 522-240, Andhra Pradesh, India.

Email: [email protected]

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Pushpa Selvi M

Pushpa Selvi M

Department of Physics and Research Centre, Lady Doak College, Madurai, Tamil Nadu, India

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Nimma Elizabeth R

Nimma Elizabeth R

Department of Physics and Research Centre, Lady Doak College, Madurai, Tamil Nadu, India

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Deepak S. Gavali

Deepak S. Gavali

Department of Physics, SRM University—AP, Amaravati, Andhra Pradesh, India

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Ranjit Thapa

Corresponding Author

Ranjit Thapa

Department of Physics, SRM University—AP, Amaravati, Andhra Pradesh, India

Correspondence

Sinthika S, Department of Physics and Research Centre, Lady Doak College, Madurai 625002, Tamil Nadu, India.

Email: [email protected]

Ranjit Thapa, Department of Physics, SRM University—AP, Amaravati 522-240, Andhra Pradesh, India.

Email: [email protected]

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First published: 13 November 2021
Citations: 9

Sinthika S. and Pushpa Selvi M. contributed equally to this work.

Funding information: Ministry of New and Renewable Energy, Government of India, Grant/Award Number: 31/03/2014-15/PVSE-R&D

Summary

Using first-principles calculations, we investigate a family of doped graphene nanoribbons (GNRs) for their suitability as cathode hosts in lithium-sulfur batteries. We probe the role played by the lone pairs of the dopants in confining the lithium polysulfides (LiPS) to understand the mechanism of binding. Our results show that the Li bond between the polysulfides and the doped GNRs is analogous to a hydrogen bond and also dipole-dipole interactions play a key role in anchoring the polysulfides. A critical donor-Li-acceptor angle of 180° is found to be essential for proper adsorption of LiPS, highlighting the importance of the directionality of lone pairs. The charge lost by the sulfur atom of the polysulfide upon adsorption and shape of the lone pair basins and the value of Electron Localization Function (ELF) at the dopant position can provide a quick estimate of the strength of the bond. Significant contractions in the ELF profiles are also observed upon Li2S adsorption, further providing evidence for the hydrogen bond-like nature of the Li bond. Our results corroborate the fact that all acceptors capable of forming hydrogen bonds can be employed as suitable dopants for carbon-based cathode hosts in Li-S batteries.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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