title: Face-centered-cubic lithium crystals formed in mesopores of carbon nanofiber electrodes.
abstract: 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.
authors.affiliation: Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
authors.forename: Byoung-Sun
authors.initials: BS
authors.lastname: Lee
authors.forename: Jong-Hyun
authors.initials: JH
authors.lastname: Seo
authors.forename: Seoung-Bum
authors.initials: SB
authors.lastname: Son
authors.forename: Seul Cham
authors.initials: SC
authors.lastname: Kim
authors.forename: In-Suk
authors.initials: IS
authors.lastname: Choi
authors.forename: Jae-Pyoung
authors.initials: JP
authors.lastname: Ahn
authors.forename: Kyu Hwan
authors.initials: KH
authors.lastname: Oh
authors.forename: Se-Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Woong-Ryeol
authors.initials: WR
authors.lastname: Yu
mesh_terms: D002244:Carbon / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004553:Electric Conductivity; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008094:Lithium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D016062:Porosity; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D002244:Carbon; D008094:Lithium