Skip to content

ReaxFF reactive force field simulations on the influence of Teflon on electrolyte decomposition during Li/SWCNT anode discharge in lithium-sulfur batteries

Evidence and attribution

Authority of statements

Prose below summarizes the JES article identified by doi, title, and pdf_path. The corpus PDF is the electrochemical society layout for this focus issue paper (not a separate proof sibling listed in NON_PRIMARY_ARTICLE_PAPER_SLUGS.md for a different slug).

Summary

Lithium–sulfur batteries offer high theoretical capacity but face polysulfide shuttle, lithium dendrites, and aggressive electrolyte reduction at the negative electrode. Replacing bare lithium metal with a Li/single-wall carbon nanotube (SWCNT) composite anode and using TEGDME (tetra(ethylene glycol) dimethyl ether) as a model ether electrolyte, this study applies ReaxFF reactive molecular dynamics to compare bare versus ex situ Teflon-coated anode surfaces during discharge. In lithium-rich interfacial regions, the simulations show TEGDME dissociation with ethylene as a major gaseous product. Discharge at the anode is exothermic, producing local hot spots that accelerate electrolyte attack. A Teflon surface layer is found to damp initial heat flow and suppress lithium-driven electrolyte decomposition relative to the uncoated interface in the modeled scenarios.

The composite architecture matters because SWCNTs provide conductive scaffolding and interfacial area where lithium deposition and solvent contact can be spatially heterogeneous; the paper uses that geometry to interrogate how a fluoropolymer skin changes heat and reaction pathways at the earliest stages of reduction.

Methods

Force field. ReaxFF parametrization for Li, carbon nanotube chemistry, ether solvents, and fluoropolymer interactions as described in the article and Supporting Information references.

Systems. Composite anode models with explicit TEGDME; variants include bare SWCNT-supported lithium versus Teflon-treated surface preparation mimicking ex situ coating.

Protocol. Reactive MD trajectories sample interfacial regions during processes analogous to discharge (lithium redistribution and reactivity toward solvent); analysis tracks bond-breaking channels, gas evolution, and temperature localization.

1 — MD application (Li/SWCNT + TEGDME)

  • Engine / code / PBC / timestep / thermostat / barostat / duration / temperature schedules: N/A — not stated on normalized/extracts/2014islam-venue-paper_p1-2.txt and not duplicated reliably here; read papers/Islam_JES_2014.pdf J. Electrochem. Soc. 161 (8) E3009–E3014 Computational section (and SI if referenced).
  • System size & composition: Li/SWCNT composite anode regions with explicit TEGDME-family solvent chemistry as described in the JES article (Summary); atom counts are N/A — not on the indexed extract (Computational section).
  • Ensemble: N/A — NVT/NPT choice not stated on the indexed extract (Computational section).
  • Hydrostatic pressure / barostat: N/A — pressure control not stated on the indexed extract (confirm whether strictly constant-volume interfacial sampling).
  • Electric field: N/A — not indicated in the abstract-level corpus summary used for this page.
  • Replica / enhanced sampling: N/A — not indicated in the abstract-level summary used here.

Findings

Ethylene emerges as a prominent decomposition product when the electrolyte interacts with lithium-rich zones at the anode interface. Thermal localization from exothermic discharge steps couples positively with decomposition kinetics. Teflon mitigates early heat transfer into the electrolyte and reduces lithium reactivity toward solvent in the simulations, consistent with the abstract’s protective framing.

Mechanistic reading. The protective effect is framed partly as thermal management at the interface: slowing localized heating reduces the rate of solvent cleavage even when thermochemistry remains favorable at equilibrium.

Electrolyte scope. TEGDME is a model ether electrolyte for Li–S research; translating conclusions to carbonate or fluorinated electrolytes requires different ReaxFF parameter domains and was not attempted in this JES study.

Limitations

extraction_quality is marked partial in corpus profiling—confirm numerical rates and full reaction lists on the PDF. Long-timescale SEI evolution and cell-level transport are not captured in nanosecond-class trajectories.

Relevance to group

van Duin-group contribution to Li–S interfacial chemistry and protective coatings on nanostructured anodes.

Citations and evidence anchors

  • J. Electrochem. Soc. 161 (8) E3009–E3014 (2014); DOI 10.1149/2.005408jes (papers/Islam_JES_2014.pdf).
  • Extract pointer: normalized/extracts/2014islam-venue-paper_p1-2.txt.