Functionalized Hf3C2 and Zr3C2 MXenes for suppression of shuttle effect to enhance the performance of sodium–sulfur batteries

Author(s)
Khan, Saba
Kumar, Narender
Hussain, Tanveer
Tit, Nacir
Publication Date
2023-10-01
Abstract
<p>Sodium-sulfur batteries show great potential for storing large amounts of energy due to their ability to undergo a double electron-redox process, as well as the plentiful abundance of sodium and sulfur resources. However, the shuttle effect caused by intermediate sodium polysulfides (Na<sub>2</sub>S<sub>n</sub>) limits their performance and lifespan. To address this issue, here we propose using Hf<sub>3</sub>C<sub>2</sub>T<sub>2</sub> and Zr<sub>3</sub>C<sub>2</sub>T<sub>2</sub> (T = F, O), two functionalized MXenes, as cathode additives to suppress the shuttle effect. By using density-functional theory calculations, we investigate nature of the interactions between Na<sub>2</sub>S<sub>n</sub> and MXene, such as the strength of adsorption energy, the electronic density of states, the charge exchange, and the dissociation energy of the Na<sub>2</sub>S molecule. Our findings show that both Hf<sub>3</sub>C<sub>2</sub>T<sub>2</sub> and Zr<sub>3</sub>C<sub>2</sub>T<sub>2</sub> systems inhibit the shuttle effect by binding to Na<sub>2</sub>S<sub>n</sub> with a binding energy stronger than the commonly used electrolyte solvents. These MXenes retain their metallicity during this process and the decomposition barrier for Na<sub>2</sub>S<sub>n</sub> on the oxygen-functionalized MXenes gets reduced which enhances the electrochemical process. Among the MXene systems studied, Zr<sub>3</sub>C<sub>2</sub>T<sub>2</sub> shows the best performance in suppressing the shuttle effect and catalyzing the electrochemistry process and, thus, increasing the battery's reversible capacity and lifespan.</p>
Citation
Journal of Power Sources, v.580, p. 1-11
ISSN
1873-2755
0378-7753
Link
Publisher
Elsevier BV
Rights
Attribution 4.0 International
Title
Functionalized Hf3C2 and Zr3C2 MXenes for suppression of shuttle effect to enhance the performance of sodium–sulfur batteries
Type of document
Journal Article
Entity Type
Publication

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