Understanding fluorine-free electrolytes via small-angle X-ray scattering

Kun Qian, Zhou Yu, Yuzi Liu, David J. Gosztola, Randall E. Winans, Lei Cheng, Tao Li

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Fluorine-free electrolytes have attracted great attention because of its low-cost and environmental friendliness. However, so far, little is known about the solution structures of these electrolytes. Here, we compare the solvation phenomenon of sodium tetraphenylborate (NaBPh4) salt dissolved in organic solvents of propylene carbonate (PC), 1,2-dimethoxyethane (DME), acetonitrile (ACN) and tetrahydrofuran (THF). Small-angle X-ray scattering (SAXS) reveals a unique two-peak structural feature in this salt-concentrated PC electrolyte, while solutions using other solvents only have one scattering peak. Molecular dynamics (MD) simulations further reveal that there are anion-based clusters in addition to the short-range charge ordering in the concentrated NaBPh4/PC electrolyte. Raman spectroscopy confirms the existence of considerable contact ion pairs (CIPs). This work emphasizes the importance of global and local structural analysis, which will provide valuable clues for understanding the structure-performance relationship of electrolytes.

Original languageEnglish
Pages (from-to)340-346
Number of pages7
JournalJournal of Energy Chemistry
Volume70
DOIs
StatePublished - Jul 2022
Externally publishedYes

Keywords

  • Fluorine-free electrolytes
  • Small-angle X-ray scattering
  • Sodium tetraphenylborate
  • Sodium-ion batteries
  • Solvation structures

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