The influence of water on the cycling behavior of the polypyrrole electrode in lithium cells
- Bonn Univ. (Germany, F.R.). Inst. fuer Physikalische und Theoretische Chemie
Two different types of polypyrrole (PPy) have been synthesized: the dry form from 0.2{ital M} pyrrole (Py) + 0.5{ital M} LiClO{sub 4} propylene carbonate (PC) and the wet one from 0.2{ital M} Py + 0.56{ital M} H{sub 2}O + 0.5{ital M} LiClO{sub 4} in PC. The polymerization of pyrrole in both electrolytes starts at + 3.46 V ({ital vs}. Li/Li{sup +}) and follows nearly the same {ital E-I} curve. During the first discharge clear differences in electrochemical behavior can already be seen. During the first 1,000 cycles performed on 1-{mu}m thin PPy layers in the dry 0.5{ital M} LiClO{sub 4} (PC) electrolyte, the coulombic capacity of the dry form of PPy dropped to about 80% of its initial value. The cycling behavior of the wet form is even better---the doping level is slightly higher and the capacity drops to 80% of its initial value after more than 20,000 cycles, when cycled in the optimum potential interval from 2.0 to 4.0 V ({ital vs}. Li/Li{sup +}). Cyclic voltammograms and {ital in situ} FTIR measurements revealed that there is a gradual, slight loss of the most negative redox sites with increasing cycle number, accompanied by an increase in the amount of the irreversibly (over)oxidized PPy found in the neutral form of the polymer. The self-discharge loss on {approx} 50-{mu}m-thick PPy foils was found to be about 1% per day.
- OSTI ID:
- 6731180
- Journal Information:
- Journal of the Electrochemical Society; (USA), Vol. 137:4; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LITHIUM
ELECTRIC BATTERIES
PYRROLES
POLYMERIZATION
ELECTRODES
ENERGY LOSSES
INFRARED SPECTRA
PERFORMANCE TESTING
SOLID ELECTROLYTES
WATER INFLUX
ALKALI METALS
AZOLES
CHEMICAL REACTIONS
ELECTROCHEMICAL CELLS
ELECTROLYTES
ELEMENTS
HETEROCYCLIC COMPOUNDS
LOSSES
METALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
SPECTRA
TESTING
250902* - Energy Storage- Batteries- Performance & Testing
400400 - Electrochemistry