Anion π-πStacking for Improved Lithium Transport in Polymer Electrolytes

Lixin Qiao, Sergio Rodriguez Peña, María Martínez-Ibañez, Alexander Santiago, Itziar Aldalur, Elias Lobato, Eduardo Sanchez-Diez, Yan Zhang, Hegoi Manzano, Haijin Zhu, Maria Forsyth, Michel Armand*, Javier Carrasco*, Heng Zhang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Polymer electrolytes (PEs) with excellent flexibility, processability, and good contact with lithium metal (Li°) anodes have attracted substantial attention in both academic and industrial settings. However, conventional poly(ethylene oxide) (PEO)-based PEs suffer from a low lithium-ion transference number (TLi+), leading to a notorious concentration gradient and internal cell polarization. Here, we report two kinds of highly lithium-ion conductive and solvent-free PEs using the benzene-based lithium salts, lithium (benzenesulfonyl)(trifluoromethanesulfonyl)imide (LiBTFSI) and lithium (2,4,6-triisopropylbenzenesulfonyl)(trifluoromethanesulfonyl)imide (LiTPBTFSI), which show significantly improved TLi+and selective lithium-ion conductivity. Using molecular dynamics simulations, we pinpoint the strong π-πstacking interaction between pairs of benzene-based anions as the cause of this improvement. In addition, we show that Li°∥Li° and Li°∥LiFePO4cells with the LiBTFSI/PEO electrolytes present enhanced cycling performance. By considering π-πstacking interactions as a new molecular-level design route of salts for electrolyte, this work provides an efficient and facile novel strategy for attaining highly selective lithium-ion conductive PEs.

Original languageEnglish
Pages (from-to)9806-9816
Number of pages11
JournalJournal of the American Chemical Society
Volume144
Issue number22
DOIs
StatePublished - 8 Jun 2022
Externally publishedYes

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