Effect of Li Content on the Cycling Performance of High Voltage, High Capacity LixMn1.5Ni0.5Oy Cathodes

Recently, extensive research has been done to optimize lithium-ion rechargeable batteries (LIBs) for vehicle, military and grid applications. LIBs are preferred when compared to other secondary batteries due to their high voltage and high energy density. However, the capacity of current cathode materials used for LIBs is limited. Improvements in rate capability and capacity can insure a longer cycle life and enhance LIBs. Lithium manganese nickel oxide, LiMn1.5Ni0.5O4 (LMNO) is a promising candidate because of high voltage operation. However, dissolution of manganese due to reaction with electrolytes and lower capacity is still a concern. Recently, several groups have reported an integrated layered-spinel composite cathodes using LMNO and Li2Mn0.6Ni0.2O3 to form LixMn1.5Ni0.5Oy (x=1.0~3.0). 1-6 These composite cathodes have shown better performances than the layered or spinel cathodes with respect to specific capacity and cyclability. One strategy is to study the effect of Li content in LMNO and investigate its structural characteristics and cycling performances. The LixMn1.5Ni0.5Oy sample show high capacity only when the Li content is above 2.0. We will report in detail about the synthesis of LixMn1.5Ni0.5Oy (x=2.0-3.0) cathodes and its electrochemical performances for lithium ion batteries.