Synthesis And Modification Of Spinel Lithium Manganese Oxide By High-temperature Solid-phase

Lithium-ion batteries has broad application prospects in electric cars and hybrid vehiclesbecause of its high energy, long life, low consumption, less pollution, no memory effect andetc. And cathode material costs accounts for more than40%of the cost of the battery,moreover, it plays a decisive role to the performance of the battery. The spinel lithiummanganese oxides cathode material is expected to become the ideal power source for electricvehicles and hybrid vehicles for its rich source low-cost, clean, safe and etc.In this thesis, based on the requirements of industrial production, we synthesized spinelLiMn2O4cathode materials by wet mechanical activation solid-state. By optimizing thesynthesis process, the spine cathode materials with high performance and good stability wereobtained. The sample prepared by optimal process, its initial dis-charge capacity is about108.3mAh/g，and the capacity retention is80.63%after50cycles when glvanostatic charge-discharge tests at0.1C rate at room temperature.On the basis of solid-phase synthesis of spinel lithium manganese oxide, the Alumina isdoped to the cathode material for modification. Studies have showed that doping does notchange the structure of spinel, and its stability has been greatly improved than the undopedlithium manganate. With suitable doping, the LiAl0.07Mn1.93O4samples peform best. Its firstdischarge capacity is up to118mAh g-1and its cycle stability and rate capability has greatlyimproved.when tests at0.1C.In addition, we also synthesis carbon–coated LiAl0.07Mn1.93O4/C composite materia byspray drying and pyrolysis process. The results showed that, the sample maintains the originalstructure of spinel lithium manganese oxide after carbon-coated and the electrochemicalperformance is much better than the doped and undoped spinel lithium manganese oxide.When modified by2wt.%sucrose its discharge capacity is84mAhg-1,and with littleattenuation after30cycles at2.0C rate, whereas pure lithium manganese oxide spineldischarge capacity is60mAh g-1, and the fastest decline in capacity, more than24.2%lostafter30cecles.