Self-terminating, heterogeneous solid–electrolyte interphase enables reversible Li–ether cointercalation in graphite anodes

Dawei Xia, Heonjae Jeong, Dewen Hou, Lei Tao, Tianyi Li, Kristin Knight, Anyang Hu, Ethan P. Kamphaus, Dennis Nordlund, Sami Sainio, Yuzi Liu, John R. Morris, Wenqian Xu, Haibo Huang, Luxi Li, Hui Xiong, Lei Cheng, Feng Lin

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Ether solvents are suitable for formulating solid-electrolyte interphase (SEI)-less ion-solvent cointercalation electrolytes in graphite for Na-ion and K-ion batteries. However, ether-based electrolytes have been historically perceived to cause exfoliation of graphite and cell failure in Li-ion batteries. In this study, we develop strategies to achieve reversible Li–solvent cointercalation in graphite through combining appropriate Li salts and ether solvents. Specifically, we design 1M LiBF4 1,2-dimethoxyethane (G1), which enables natural graphite to deliver ~91% initial Coulombic efficiency and >88% capacity retention after 400 cycles. We captured the spatial distribution of LiF at various length scales and quantified its heterogeneity. The electrolyte shows self-terminated reactivity on graphite edge planes and results in a grainy, fluorinated pseudo-SEI. The molecular origin of the pseudo-SEI is elucidated by ab initio molecular dynamics (AIMD) simulations. The operando synchrotron analyses further demonstrate the reversible and monotonous phase transformation of cointercalated graphite. Our findings demonstrate the feasibility of Li cointercalation chemistry in graphite for extreme-condition batteries. The work also paves the foundation for understanding and modulating the interphase generated by ether electrolytes in a broad range of electrodes and batteries.

Original languageEnglish
Article numbere2313096121
JournalProceedings of the National Academy of Sciences of the United States of America
Volume121
Issue number5
DOIs
StatePublished - 2024
Externally publishedYes

Keywords

  • cointercalation
  • ether electrolytes
  • graphite anode
  • Li-ion batteries
  • solid-electrolyte interphase

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