Raman spectroscopy and electron microscopy of heat-treated petroleum cokes for lithium-intercalation electrodes
- Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.
- Lawrence Livermore National lab., CA (United States). Dept. of Chemistry and Materials Science
Raman spectroscopy, coupled with high-resolution transmission electron microscopy (HRTEM) and x-ray diffraction analysis, were used to characterize the physical properties of carbonaceous materials obtained by heat-treatment of petroleum coke at 1800, 2100, and 2350 C. The effects of heat-treatment and air milling process (to obtain an average particle size of 10 {micro}m) on the physical and microstructural properties of the carbon particles were examined. The Raman intensities of the D and G bands were used to estimate the crystallite size, L{sub a}, and x-ray diffraction was used to obtain L{sub c} and the d(002) spacing of the petroleum cokes. Heat-treatment of the petroleum coke at temperatures above 2100 C produces a L{sub a} value of about 100 {angstrom}, interplanar distance, L{sub c}, of >600 {angstrom}, and d(002) spacing of 3.358 {angstrom}, close to that of graphite. HRTEM showed that a distinct ordering of the layer planes occurs with heat-treatment, and a perceptible difference in the surface morphology is evident with petroleum coke that is heat-treated at 2350 C and then air milled. The electrochemical results for lithium intercalation/deintercalation of the petroleum cokes in 0.5 M LiN(CF{sub 3}SO{sub 2}){sub 2}/ethylene carbonate:dimethyl carbonate electrolyte revealed that heat-treatment at 2350 C improves the reversible Li storage capacity of the petroleum coke, and that air milling after heat-treatment produces a petroleum coke with high reversible capacity, equivalent to Li{sub 0.93}C{sub 6}.
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098; W-7405-ENG-48
- OSTI ID:
- 556831
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 9; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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