Face-Centered-Cubic Lithium Crystals Formed in Mesopores of Carbon Nanofiber Electrodes

In the foreseeable future, there will be a sharp increase in the demand for flexible Li-ion batteries. One of the most important components of such batteries will be a freestanding electrode, because the traditional electrodes are easily damaged by repeated deformations. The mechanical sustainabilit...

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Bibliographic Details
Published in:ACS nano 2013-07, Vol.7 (7), p.5801-5807
Main Authors: Lee, Byoung-Sun, Seo, Jong-Hyun, Son, Seoung-Bum, Kim, Seul Cham, Choi, In-Suk, Ahn, Jae-Pyoung, Oh, Kyu Hwan, Lee, Se-Hee, Yu, Woong-Ryeol
Format: Article
Language:English
Subjects:
Carbon
Carbon - chemistry
Carbon fibers
Crystallization - methods
Crystals
Electric Conductivity
Electrodes
Equipment Design
Equipment Failure Analysis
Face centered cubic lattice
Holes
Lithium
Lithium - chemistry
Macromolecular Substances - chemistry
Materials Testing
Molecular Conformation
Nanofibers
Nanofibers - chemistry
Nanofibers - ultrastructure
Nanostructure
Particle Size
Porosity
Surface Properties
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Summary:In the foreseeable future, there will be a sharp increase in the demand for flexible Li-ion batteries. One of the most important components of such batteries will be a freestanding electrode, because the traditional electrodes are easily damaged by repeated deformations. The mechanical sustainability of carbon-based freestanding electrodes subjected to repeated electrochemical reactions with Li ions is investigated via nanotensile tests of individual hollow carbon nanofibers (HCNFs). Surprisingly, the mechanical properties of such electrodes are improved by repeated electrochemical reactions with Li ions, which is contrary to the conventional wisdom that the mechanical sustainability of carbon-based electrodes should be degraded by repeated electrochemical reactions. Microscopic studies reveal a reinforcing mechanism behind this improvement, namely, that inserted Li ions form irreversible face-centered-cubic (FCC) crystals within HCNF cavities, which can reinforce the carbonaceous matrix as strong second-phase particles. These FCC Li crystals formed within the carbon matrix create tremendous potential for HCNFs as freestanding electrodes for flexible batteries, but they also contribute to the irreversible (and thus low) capacity of HCNFs.
ISSN:1936-0851
1936-086X
DOI:10.1021/nn4019625