Electrochemical intercalation of PF{sub 6} into graphite

Journal Article · Wed Mar 01 04:00:00 EST 2000 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1393288· OSTI ID:20030644

Seel, J A; Dahn, J R

Nonaqueous electrochemical cells using carbon as both the negative and positive electrodes have been proposed in the literature. In such dual graphite cells, lithium intercalculates into the negative electrode, and the anion intercalates into the positive electrode when the cells are charged, depleting the electrolyte of salt. Here, the origin of the cell potential is considered first. Then using Li/graphite test cells, PF{sub 6} intercalation into graphite is studied using electrochemical methods and in situ X-ray diffraction. The authors prove that PF{sub 6} intercalated graphite exists in a series of stages phases. Differential capacity vs. voltage measurements are used to determine the voltages of the staging transitions and the compositions of the stages phases. The cell potential during anion intercalation rises to over 5 V, and they have learned that cells with electrolytes using ethyl methyl sulfone solvent can give reliable results up to 5.5 V under these highly oxidizing conditions. By contrast, ethylene carbonate based electrolytes are strongly oxidized above about 5.2 V, preventing complete loading of graphite with PF{sub 6}.

• Research Organization: Dalhousie Univ., Halifax, Nova Scotia (CA)
• OSTI ID: 20030644
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 3 Vol. 147; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
36 MATERIALS SCIENCE
ELECTROCHEMICAL CELLS
ELECTRODES
GRAPHITE
LITHIUM COMPOUNDS
NONAQUEOUS SOLVENTS
PHOSPHORUS FLUORIDES