Charge-discharge properties of chemically prepared composites of V2O5 and polypyrrole as positive electrode materials in rechargeable Li batteries

The composite powder of V2O5 and polypyrrole (V2O5/PPy) was prepared by chemical polymerization of pyrrole using V2O5 powder dispersed in an acidic solution as an oxidizing agent. The composites containing V2O5 in its amount ranging from 30 to 94 w/o were prepared from the preparation baths containing different amounts of dispersed V2O5 powder. Pellets of V2O5/PPy were prepared by pressing the composite powder without any binder. The prepared V2O5/PPy pellets exhibited charge-discharge curves characteristics of redox reaction of V2O5 (V2O5 + xLi(+) + e(-) = LixV2O5 (0 less than or equal to x less than or equal to 1)), indicating that PPy worked well as binding material as well as conducting matrix. The effects of charge-discharge current densities and amounts of V2O5 in the composite were investigated. Cycle tests conducted by using the composite containing 91 w/o V2O5 revealed that 100 times repetition did not cause significant decrease in the capacity. The reaction scheme during the course of charge and discharge of the composite was investigated by its electrochemical behavior and elemental analysis. (C) 2000 Elsevier Science Ltd. All rights reserved.