Preparation of Mn-substituted LiFeO2:: A solid solution of LiFeO2 and LixMnO2

A new type of LiFeO2-LixMnO2 solid solution was synthesized at 350degreesC under argon flow by a solid-state reaction. The doped Mn ions in the LiMnxFe1-xO2 (0less than or equal toxless than or equal to0.5) obtained at 150degreesC were regarded as an impurity in the orthorhombic LiFeO2 structure and failed to form a perfect substitution form due to the low synthesis temperature. However, the LiFeO2-LixMnO2 solid solutions with various Mn contents (Mn/(Fe+Mn)=0.1-0.5) were successfully obtained by calcination at 350degreesC. Especially, the XRD pattern of the 50% Mn-substituted LiFeO2 material was very similar to that of a lithiated LixMnO2 compound. The Li/50% Mn-substituted LiFeO2 cell exhibited not only a distinct increased voltage plateau in the 2.8 V region, but also an excellent cycling performance up to 50 cycles. We believe that this LiFeO2-LixMnO2 solid solution type compound has a unique electrochemical property in the cycling process. (C) 2003 Elsevier Science B.V. All rights reserved.