Solid Match Chemical Reaction Synthesis Of Lithium-ion Battery Cathode Materials Of Limn <sub> 2 </ Sub> The O <sub> 4 </ Sub> And Its Doped Material

In this paper, ultrafmed spinel LiMn2O4 and the doped LiMn2O4 were synthesized by solid state coordination reaction. The preparing technological parameters, structure, formation mechanism and properties of LiMn2O4 and the doped LiMn2O4 were systematically studied and discussed.The ratios of primary materials and calcining temperature were studied systematically. The ratios of lithium nitrate, manganese acetate and citric acid are 1:2:3, and the optimum calcining temperature is 500~550℃.The spinel LiMn2O4 calcined at 550℃ attained pure phase and high crystllinity. The content of lithium is 3.79%(w/o), which is similar to the theory content (3.84%) of LiMn2O4 compound. The particle size of LiMn2O4 cathode prepared at 550℃ is fine, and the powder within particle size ranges of 0.06~0.5um amount 82.10% of the total. The specific surface area and the average particle size of the LiMn2O4 powder are 10.15m2/g and 138.12nm, respectively. The morphology of the powder show porous structure and are aggregative. The voltage plateaus of charge are 4.05V and 4.15V, and the discharge are 4.10V and 3.95V. The first discharge specific capacity is 124.2 mAh/g, and the material have good cyclability. The tenth discharge specific capacity is 109.8 mAh/g, which is 88.4% of the first discharge specific capacity.The LiMxMn2-xO4(M=Ni, Co, Cr, Al, x=0.05, 0.10, 0.15, 0.20) materials maintain spinel structure, in which the doped elements form solution. In the doped materials, the smaller M3+ substitut larger Mn3+, which decreases lattice parameter and stabilizes spinel structure. The particle size is fine and the morphology is porous. With the increasing of doping concentration, the discharge specific capacity decrease. The LiM0.10Mn1.90O4(M=Ni, Co, Cr, Al) materials have stable spinel structure and good cycleability. The Co or Ni doped materials have the best cycleability. The fifth discharge specific capacity of LiCo0.10Mn1.90O4 and LiNi0.10Mn1.90O4 materials are 119.5mAh/g and 118.0mAh/g, which were97.2% and 96.3% of the first discharge specific capacity, respectively.