The electrochemical intercalation of Li into graphite in Li/polymer electrolyte/graphite cells
- EIC Labs., Inc., Norwood, MA (United States)
The electrochemical intercalation of Li into graphite has been studied in Li/polymer electrolyte/graphite cells using an in situ X-ray diffraction (XRD) technique. In cells containing an electrolyte of PAN (polyacrylonitrile)-EC (ethylene carbonate)-LiPF{sub 6}, a minor irreversible reduction of the electrolyte is observed only during the first discharge. In these cells, Li is reversibly intercalated into graphite to form Li{sub 1.0}C{sub 6}, principally at potentials between 0.2 and 0.0 V vs. Li{sup +}/Li. No evidence for the cointercalation of EC was obtained. In cells containing PAN-EC/PC(propylene carbonate)-LiPF{sub 6}-based electrolyte, a massive reduction of electrolyte occurs during the first discharge at {approximately}0.8 V vs. Li{sup +}/Li, which precludes Li intercalation into graphite. In situ XRD data are consistent with the absence of the intercalation of PC or Li{sup +}(PC){sub n} solvates into the graphite lattice, either prior to or during the solvent reduction process. The latter appears to be a surface-catalyzed process, the extent of which is determined by a combination of thermodynamic and kinetic factors including the reduction potential of the electrolyte, and the passivating films which form on the graphite surface as a result of electrolyte reduction.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 61488
- Journal Information:
- Journal of the Electrochemical Society, Vol. 142, Issue 2; Other Information: PBD: Feb 1995
- Country of Publication:
- United States
- Language:
- English
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