The Synthesis And Properties Improvement Of Cathode Material LiMnO₂ For Lithium-ion Battery

Lithium-ion battery is a new type of secondary batteries developed during 1990's.Lithium manganese oxides have advantages as the positive active materials for lithium-ion batteries, such as nontoxicity, low cost etc. However, the capacity fade of lithium manganese oxides made its application difficulty. Recently, a new layered LiMnO2 which have more high capacity than spinel LiMNO2), has become the hot topic of cathode of lithium-ion batteries.In this paper, we have introduced a new synthesis method-rheological phase reaction method, which is a simple, rapid and cost-effective process for obtaining oxide powders. By this method, we successfully synthesized orthorhombic LiMnO2. Its lattice parameters are a=0.4569nm, b = 0.5744nm, c = 0.2795nm, a = p= 90? The electrode of o-LiMnO2 show electrochemical properties with a discharge capacity of 11 OmAh/g after 11 cycles and retaining 103.6mAh/g after 39 cycles at a current rate of 25mA/g at room temperature.Layered monoclinic LiMnO2 was synthesized by soft chemistry synthesis method. First, Layered NaMnOa with a monoclinic structure was synthesized by rheological phase reaction method, then the precursor was used to prepare layered LiMnO2 by solvothermal method .The lattice parameters of the LiMnO2 are a=0.54211nm, b=0.28103nm, c=0.53903nm, ?115.96? The electrode of m-LiMnO2 show electrochemical properties with a first discharge capacity of 131mAh/g and retaining 128mAh/g after 30 cycles at a current rate of 25mA/g at room temperature.At the last, orthorhombic LixMnO2 (0.9x1.10) , monoclinic LiAloiMn09O2 and LiCro.osMno.95O2 were synthesized by rheological phase reaction method. The electrode of Lii.osMnC^ show electrochemical properties with a discharge capacity of 114.7mAh/g after 40 cycles, so the electrode of LiuoMnOa is 118.5 mAh/g. The electrode of LiAlo.iMno.9O2 show electrochemical properties with a first discharge capacity of 141.7mAh/g and retaining 124.1 mAh/g after 10 cycles; the electrode of LiCro.osMno95O2 show electrochemical properties with a first discharge capacity of 155.1 mAh/g and retaining 126.3mAh/g after 10 cycles.