Formation of lithium-graphite intercalation compounds in nonaqueous electrolytes and their application as a negative electrode for a lithium ion (shuttlecock) cell

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2220849· OSTI ID:5896110

Ohzuku, Tsutomu; Iwakoshi, Yasunobu; Sawai, Keijiro ^[1]

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1. Osaka City Univ., Osaka (Japan). Dept. of Applied Chemistry

Electrochemical reduction of natural graphite was carried out in 1M LiClO[sub 4] ethylene carbonate (EC)/1,2-dimethoxyethane (DME) solution at 30 C. Natural graphite was reduced stepwise to LiC[sub 6]. The staging phenomenon was observed by X-ray diffraction (XRD). The first stage and the second stage compounds were identified as a commensurate structure in which lithium atoms form a close-packed two-dimensional array. A second-stage compound (LiC[sub 18]) with a different in-plane lithium ordering based on a LiC[sub 9] two-dimensional packing in lithium intercalated sheets also was observed; also third, fourth-stage compounds were identified. The electrochemical oxidation of the first-stage compound (LiC[sub 6]) was examined and shown to reversible over the entire range, i.e., C[sub 6] + xLi [r reversible] Li[sub x]C[sub 6]. The reaction mechanism for the reduction of graphite and the oxidation of the first-stage compound are discussed in relation to the staging phenomenon from the detailed open-circuit voltage and XRD data. The chemical potential of LiC[sub 6] was estimated to be [minus]3.6 kcal mol from the observed reversible potential. The feasibility of using a lithium-graphite intercalation compound in lithium ion (shuttlecock) cells is described, and the innovative secondary systems, C[sub 6]/LiCoO[sub 2] and C[sub 6]/LiNiO[sub 2] fabricated in discharged states, are demonstrated.

• OSTI ID: 5896110
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 140:9; ISSN 0013-4651
• Country of Publication: United States
• Language: English

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37 INORGANIC
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SYNTHESIS
CHLORATES
ELECTROCHEMISTRY
EXPERIMENTAL DATA
GRAPHITE
LITHIUM COMPOUNDS
OXIDATION
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X-RAY DIFFRACTION
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ELEMENTAL MINERALS
ELEMENTS
HALOGEN COMPOUNDS
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NONMETALS
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