Chemical preparation of manganese dioxide/polypyrrole composites and their use as cathode active materials for rechargeable lithium batteries
- Osaka Univ. (Japan). Dept. of Applied Chemistry
Chemical preparation of composite powders of polypyrrole and either {alpha}-MnO{sub 2}, {beta}-MnO{sub 2}, or spinel LiMn{sub 2}O{sub 4} has been successfully achieved by injecting liquid pyrrole into an acidic medium containing suspended manganese dioxide powder as an oxidizing agent. The content of manganese dioxide in the composites increased with increasing amount of suspended manganese dioxide in the polymerization bath. The maximum content of manganese dioxide was 85, 87, and 83.3 weight percent for {alpha}-MnO{sub 2}, {beta}-MnO{sub 2}, and LiMn{sub 2}O{sub 4}, respectively. Charge-discharge tests of {beta}-MnO{sub 2}/polypyrrole and LiMn{sub 2}O{sub 4}/polypyrrole composites conducted in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane (1:1) containing 1 mol/dm{sup 3} LiClO{sub 4} have revealed that the polypyrrole worked well both as an active material and as a conducting network for manganese dioxide. The {beta}-MnO{sub 2}/polypyrrole composite gave one potential plateau in both charge and discharge curves, whereas the LiMn{sub 2}O{sub 4}/polypyrrole composite exhibited two distinct potential regions. The utilization of manganese dioxide was higher when polypyrrole was used as the conducting matrix than when carbon powder was used. Elemental analyses of the composites have revealed that both electrolyte anions and cations were involved in the charge-discharge reaction of the {beta}-MnO{sub 2}/polypyrrole composite, but electrolyte cations alone were involved in that of the LiMn{sub 2}O{sub 4}/polypyrrole composite. The mechanisms of the charge-discharge reaction of these two kinds of composites are in good conformity with the mechanism of composite formation.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 197689
- Journal Information:
- Journal of the Electrochemical Society, Vol. 142, Issue 12; Other Information: PBD: Dec 1995
- Country of Publication:
- United States
- Language:
- English
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