Understanding Structural and Transport Properties of Dissolved Li₂S₈ in Ionic Liquid Electrolytes through Molecular Dynamics Simulations

Abstract

Lithium‐sulfur batteries with high energy density are considered as one of the most promising future energy storage devices. However, the parasitic lithium polysulfides shuttle phenomenon severely hinders the commercialization of such batteries. Ionic liquids have been found to suppress the lithium polysulfides solubility, diminishing the shuttle effect effectively. Herein, we performed classical molecular dynamics simulations to explore the microscopic mechanism and transport behaviors of typical Li2S8 species in ionic liquids and ionic liquid‐based electrolyte systems. We found that the trifluoromethanesulfonate anions ([OTf]−) exhibit higher coordination strength with lithium ions compared with bis(trifluoromethanesulfonyl)imide anions ([TFSI]−) in static microstructures. However, the dynamical characteristics indicate that the presence of the [OTf]− anions in ionic liquid electrolytes bring faster Li+ exchange rate and easier dissociation of Li+ solvation structures. Our simulation models offer a significant guidance to future studies on designing ionic liquid electrolytes for lithium‐sulfur batteries.

Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries

“…The reduced average binding energy when more particles are involved in the solvation can also rationalize the divergence between solvation structures and dynamical properties observed in the IL electrolytes. OTF – anions exhibit higher coordination strength with Li + compared to TFSI – anions, but they render high diffusion coefficients of Li + . Mitigating the strong association between cations and anions is an effective approach to promoting the transport of cations.…”

“…OTF − anions exhibit higher coordination strength with Li + compared to TFSI − anions, but they render high diffusion coefficients of Li + . 415 Mitigating the strong association between cations and anions is an effective approach to promoting the transport of cations. This can be achieved by introducing ARs into electrolytes, which are good at This AR traps PF 6 − more strongly than the popular TPFPB to reduce the formation of ion pairs, delivering a much larger ionic conductivity and cationic transference number.…”

Amino‐functionalized SiO 2 modified porous polyetherimide separator for high performance Li‐S batteries

“…5 Aiming at these issues, numerous efforts have been devoted to this area. [6][7][8][9][10][11][12] Of these, separator modification and functionalization provide an attractive solution by virtue of its simplicity and effectiveness. [13][14][15] As an important part of Li-S batteries, the separator prohibits the cutting-out of batteries and acts as the channel to transport lithium ions between electrodes.…”

Balancing Anchoring and Diffusion for Screening of Metal Oxide Cathode Materials in Lithium–Sulfur Batteries

“…However, practical applications still face many challenges: (i) poor conductivity of S and Li 2 S, (ii) large volume expansion of S, and (iii) dissolution of lithium polysulfide intermediates (Li 2 S n , n = 1−8) in the organic electrolyte during the cycling process, leading to a shuttle effect, which can, in turn, lead to irreversible capacity attenuation, Coulomb efficiency reduction, and serious selfdischarge. 13,14 The current research on Li−S batteries mainly focuses on the strategies of capturing Li 2 S n and preventing Li 2 S n from dissolving, inhibiting the shuttle effect, and promoting electrochemical performance. Potential solutions such as anchoring materials (AMs), 15,16 protective interlayers, 17 and binders 18,19 have demonstrated their superiority in sulfur cathodes.…”

“…Therefore, the Li–S battery is considered as a promising next-generation high-energy-density battery system. However, practical applications still face many challenges: (i) poor conductivity of S and Li 2 S, (ii) large volume expansion of S, and (iii) dissolution of lithium polysulfide intermediates (Li 2 S n , n = 1–8) in the organic electrolyte during the cycling process, leading to a shuttle effect, which can, in turn, lead to irreversible capacity attenuation, Coulomb efficiency reduction, and serious self-discharge. , …”