High-performance N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide/poly(vinylidene fluoride-hexafluoropropylene) gel polymer electrolytes for lithium metal batteries

Xiaona Pan, Tianyi Liu, David J. Kautz, Linqin Mu, Chixia Tian, Timothy Edward Long, Peixia Yang, Feng Lin

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Ionically conductive polymer electrolytes represent a class of safe and environment-friendly electrolytes for next-generation alkali metal batteries. Understanding the interplay between composition-driven interfacial processes and battery performance can fundamentally inform the design of polymer electrolytes for practical applications. In this study, we fabricate lithium metal batteries based on transparent free-standing ionic liquid gel polymer electrolytes (ILGPEs) and LiFePO4 cathodes. We develop the ILGPEs using a composite of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). A thorough compositional optimization shows that the lithium ion conductivity of the ILGPE increases with the increase of PP13TFSI and LiTFSI, reaching maxima of 1.3 mS cm−1 at 23 °C and 5.82 mS cm−1 at 80 °C when the ILGPE contains 60 wt% PP13TFSI and 20 wt% LiTFSI. The optimized ILGPE exhibits excellent interfacial stability against the lithium metal, as signified by the stable interfacial resistance upon long-term storage. The LiFePO4|ILGPE|Li cells can deliver superior battery performance with a practical capacity approaching 89.5% of the theoretical capacity and capacity retention of 95.0% after 200 cycles. The formation of the electrode–electrolyte interphases takes place primarily during the initial cycles, which likely accounts for the activation period observed in LiFePO4|ILGPE|Li cells.

Original languageEnglish
Pages (from-to)127-136
Number of pages10
JournalJournal of Power Sources
Volume403
DOIs
Publication statusPublished - 2018 Nov 1
Externally publishedYes

Keywords

  • Freestanding
  • Interfacial chemistry
  • Ionic conductivity
  • Ionic liquid gel polymer electrolyte
  • Lithium metal battery

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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