A RECHARGEABLE CELL BASED ON A CONDUCTIVE POLYMER METAL ALLOY COMPOSITE ELECTRODE

A composite electrode composed of a conductive polymer and an alkali-metal alloy has been investigated as the negative electrode for a nonaqueous rechargeable cell. A sodium-alloy based composite electrode composed of Na3.75Pb, poly(p-phenylene), and binder achieved a capacity of 234 mAh/cm3. This electrode also exhibited excellent cycle life and rate capability without dendrite formation. The composite electrode exhibited kinetic behavior similar to that of pure sodium metal. A balanced cell was constructed by combining the above sodium-ion-inserting composite negative electrode with a sodium-ion-inserting positive electrode, NaxCoO2, of approximately equal capacity. The cell exhibited excellent cycle life (>250 cycles). The semiempirical energy density of the NaxCoO2/composite electrode system is comparable to alternative lithium metal based cell such as TiS2/ Li assuming that excess Li is needed in the latter case.