Cobalt can be doped into the layered alkali manganese dioxides, MxMn1-yCoyO
2 for M = K or Na, during the hydrothermal synthesis from the alkali perman
ganates. A single phase is obtained up to about 5% mol cobalt. The cobalt d
oping is found to enhance the conductivity by two orders of magnitude relat
ive to pure KxMnO2. (C) 1999 The Electrochemical Society. S1099-0062(99)05-
080-4. All rights reserved.