Abstract Lithium–sulphur (Li–S) batteries have great potential due to their high theoretical energy density. However, their functional performance is hindered by challenges such as polysulfide shuttling, variations in electrode volume, and the generation of intricate intermediates. This study examines small Li<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$_m$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mi>m</mi> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>S<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$_n$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mi>n</mi> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation> clusters (m = 2–4, n = 2–6) to investigate the processes of lithiation using a comprehensive multi-level quantum chemical framework. The computational study considers global structural searches, dispersion-corrected DFT optimisations (PBE-D3BJ/def2-SVP), and enhanced single-point energy estimates with CCSD(T)/CBS. Performance benchmarking of 49 density functionals reveals that B1LYP and DSD-PBEB95 are the most accurate for sulphur-rich and lithium-rich clusters, according to normalised mean absolute error. As the lithium concentration rises, there is a clear trend toward better three-dimensionality in the structural alteration. Alternatively, the strain produced by lithiation in experiments is consistent with the computed volume changes in Li<InlineEquation ID="IEq3"> <EquationSource Format="TEX">$_2$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>S<InlineEquation ID="IEq4"> <EquationSource Format="TEX">$_n$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mi>n</mi> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation> clusters. Their significance in polysulfide modification is highlighted by stability trends, which show that Li<InlineEquation ID="IEq5"> <EquationSource Format="TEX">$_2$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>S<InlineEquation ID="IEq6"> <EquationSource Format="TEX">$_3$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>3</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation> and Li<InlineEquation ID="IEq7"> <EquationSource Format="TEX">$_3$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>3</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>S<InlineEquation ID="IEq8"> <EquationSource Format="TEX">$_5$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>5</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation> are beneficial intermediates. These findings improve our understanding of Li-S interactions and open the door for more systematic material design efforts to improve battery longevity and efficiency. Graphical abstract

Electronic structure and stability in small lithium-sulphur clusters: A computational investigation

期刊论文
发表日期：

2025年12月5日

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Pratik Sarkar,
Anakuthil Anoop

摘要

Abstract

Lithium–sulphur (Li–S) batteries have great potential due to their high theoretical energy density. However, their functional performance is hindered by challenges such as polysulfide shuttling, variations in electrode volume, and the generation of intricate intermediates. This study examines small Li $_m$ $_{m}$ S $_n$ $_{n}$ clusters (m = 2–4, n = 2–6) to investigate the processes of lithiation using a comprehensive multi-level quantum chemical framework. The computational study considers global structural searches, dispersion-corrected DFT optimisations (PBE-D3BJ/def2-SVP), and enhanced single-point energy estimates with CCSD(T)/CBS. Performance benchmarking of 49 density functionals reveals that B1LYP and DSD-PBEB95 are the most accurate for sulphur-rich and lithium-rich clusters, according to normalised mean absolute error. As the lithium concentration rises, there is a clear trend toward better three-dimensionality in the structural alteration. Alternatively, the strain produced by lithiation in experiments is consistent with the computed volume changes in Li $_2$ $_{2}$ S $_n$ $_{n}$ clusters. Their significance in polysulfide modification is highlighted by stability trends, which show that Li $_2$ $_{2}$ S $_3$ $_{3}$ and Li $_3$ $_{3}$ S $_5$ $_{5}$ are beneficial intermediates. These findings improve our understanding of Li-S interactions and open the door for more systematic material design efforts to improve battery longevity and efficiency.

Graphical abstract