Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability

Jie Zhao, Lei Liao, Feifei Shi, Ting Lei, Guangxu Chen, Allen Pei, Jie Sun, Kai Yan, Guangmin Zhou, Jin Xie, Chong Liu, Yuzhang Li, Zheng Liang, Zhenan Bao, Yi Cui

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

Significant increases in the energy density of batteries must be achieved by exploring new materials and cell configurations. Lithium metal and lithiated silicon are two promising high-capacity anode materials. Unfortunately, both of these anodes require a reliable passivating layer to survive the serious environmental corrosion during handling and cycling. Here we developed a surface fluorination process to form a homogeneous and dense LiF coating on reactive anode materials, with in situ generated fluorine gas, by using a fluoropolymer, CYTOP, as the precursor. The process is effectively a "reaction in the beaker", avoiding direct handling of highly toxic fluorine gas. For lithium metal, this LiF coating serves as a chemically stable and mechanically strong interphase, which minimizes the corrosion reaction with carbonate electrolytes and suppresses dendrite formation, enabling dendrite-free and stable cycling over 300 cycles with current densities up to 5 mA/cm2. Lithiated silicon can serve as either a pre-lithiation additive for existing lithium-ion batteries or a replacement for lithium metal in Li-O2 and Li-S batteries. However, lithiated silicon reacts vigorously with the standard slurry solvent N-methyl-2-pyrrolidinone (NMP), indicating it is not compatible with the real battery fabrication process. With the protection of crystalline and dense LiF coating, LixSi can be processed in anhydrous NMP with a high capacity of 2504 mAh/g. With low solubility of LiF in water, this protection layer also allows LixSi to be stable in humid air (∼40% relative humidity). Therefore, this facile surface fluorination process brings huge benefit to both the existing lithium-ion batteries and next-generation lithium metal batteries.

Original languageEnglish (US)
Pages (from-to)11550-11558
Number of pages9
JournalJournal of the American Chemical Society
Volume139
Issue number33
DOIs
StatePublished - Aug 23 2017

Fingerprint

Fluorination
Halogenation
Lithium
Anodes
Electrodes
Silicon
Metals
Fluorine
Coatings
Corrosion
Gases
Dendrites
Fluorine containing polymers
Poisons
Carbonates
Ions
Electrolytes
Atmospheric humidity
Current density
Solubility

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Zhao, Jie ; Liao, Lei ; Shi, Feifei ; Lei, Ting ; Chen, Guangxu ; Pei, Allen ; Sun, Jie ; Yan, Kai ; Zhou, Guangmin ; Xie, Jin ; Liu, Chong ; Li, Yuzhang ; Liang, Zheng ; Bao, Zhenan ; Cui, Yi. / Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability. In: Journal of the American Chemical Society. 2017 ; Vol. 139, No. 33. pp. 11550-11558.
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Zhao, J, Liao, L, Shi, F, Lei, T, Chen, G, Pei, A, Sun, J, Yan, K, Zhou, G, Xie, J, Liu, C, Li, Y, Liang, Z, Bao, Z & Cui, Y 2017, 'Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability', Journal of the American Chemical Society, vol. 139, no. 33, pp. 11550-11558. https://doi.org/10.1021/jacs.7b05251

Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability. / Zhao, Jie; Liao, Lei; Shi, Feifei; Lei, Ting; Chen, Guangxu; Pei, Allen; Sun, Jie; Yan, Kai; Zhou, Guangmin; Xie, Jin; Liu, Chong; Li, Yuzhang; Liang, Zheng; Bao, Zhenan; Cui, Yi.

In: Journal of the American Chemical Society, Vol. 139, No. 33, 23.08.2017, p. 11550-11558.

Research output: Contribution to journalArticle

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AU - Zhao, Jie

AU - Liao, Lei

AU - Shi, Feifei

AU - Lei, Ting

AU - Chen, Guangxu

AU - Pei, Allen

AU - Sun, Jie

AU - Yan, Kai

AU - Zhou, Guangmin

AU - Xie, Jin

AU - Liu, Chong

AU - Li, Yuzhang

AU - Liang, Zheng

AU - Bao, Zhenan

AU - Cui, Yi

PY - 2017/8/23

Y1 - 2017/8/23

N2 - Significant increases in the energy density of batteries must be achieved by exploring new materials and cell configurations. Lithium metal and lithiated silicon are two promising high-capacity anode materials. Unfortunately, both of these anodes require a reliable passivating layer to survive the serious environmental corrosion during handling and cycling. Here we developed a surface fluorination process to form a homogeneous and dense LiF coating on reactive anode materials, with in situ generated fluorine gas, by using a fluoropolymer, CYTOP, as the precursor. The process is effectively a "reaction in the beaker", avoiding direct handling of highly toxic fluorine gas. For lithium metal, this LiF coating serves as a chemically stable and mechanically strong interphase, which minimizes the corrosion reaction with carbonate electrolytes and suppresses dendrite formation, enabling dendrite-free and stable cycling over 300 cycles with current densities up to 5 mA/cm2. Lithiated silicon can serve as either a pre-lithiation additive for existing lithium-ion batteries or a replacement for lithium metal in Li-O2 and Li-S batteries. However, lithiated silicon reacts vigorously with the standard slurry solvent N-methyl-2-pyrrolidinone (NMP), indicating it is not compatible with the real battery fabrication process. With the protection of crystalline and dense LiF coating, LixSi can be processed in anhydrous NMP with a high capacity of 2504 mAh/g. With low solubility of LiF in water, this protection layer also allows LixSi to be stable in humid air (∼40% relative humidity). Therefore, this facile surface fluorination process brings huge benefit to both the existing lithium-ion batteries and next-generation lithium metal batteries.

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