Electrochemical performance of orthorhombic LiMnO2 as cathode in lithium ion batteries

Two types of orthorhombic LiMnO2 of different stoichiometry were synthesise d using a solid-state reaction at high temperature. Their electrochemical p erformance is dependent on the synthesis conditions. It was found that a fe w charge/discharge cycles were necessary to activate the electrochemical re activity of o-LiMnO2, which is related to the transformation from the ortho rhombic phase to a spinel-like phase. AC impedance spectroscopy confirmed t his phenomenon, which showed that initially the charge-transfer resistance (R-CT) for the o-LiMnO2 electrode is much larger than that for the electrod e in the charged state. A maximum discharge capacity of 180-190 mAh/g was a chieved for the o-LiMnO2 electrode.