Electrochemistry of the layered manganese dioxides: A(x)Mn(1-y)(Co, Ni, Fe)yO(2) (A = Li, K) rate effects

Cobalt, iron, and nickel can be doped into the layered alkali manganese dio xides, A(x)Mn(1-y)M(y)O(2) for A = K, Na, or Li and M = Co, Fe, or Ni, duri ng the hydrothermal synthesis from the alkali permanganates. A single phase is obtained. The transition metal doping enhanced the electrochemical beha vior in lithium cells. The manganese phases formed during cycling appear to depend on the rate of reaction; a spinel-like phase was formed at 1 mA/cm( 2) whereas the layered phase is maintained at 0.1 mA/cm(2) independent of w hether potassium or lithium ions reside between the MnO2 layers of the stru cture. Polarization is significantly less in the spinel-like regime. (C) 20 00 The Electrochemical Society. S1099-0062(00)03-049-2. All rights reserved .