The Prepare And Studies Of Nano-LiMn₂O₄

Lithium-ion rechargeable battery is developed based on the principle of lithium ion intercalation and deintercalation on a carbon negative electrod and intercalation compound positive electrode. It has the merit of higher energy density, good cycling stabisity and higher voltage. And it has wide prospection of commercial and applying in the field of communication, instrument, medicinal apparatus, salvage, avigation and so on.The positive elsctrode material is the most important technology for lithium-ion rechargeable battery. The research of positive electrode began from LiCoO2, LiNiO2 to LiMn2O4. It costed only several decades. Comparing to LiCoO2 or LiNiO2 based cathode materials, spinel LiMn2O4 are recognized for their superiority for the safety program and low cost. And LiMn2O4 has already commericialized in some markets.Nano-materials show many specific performances in electrochemically. The spinel nano-LiMn2O4 used as cathode for Li-ion batter was synthesized by Sol-gel method in this paper. The dependence of physicochemical properties of the spinel nano-liMn2O4 powdwes on the Li / Mn mole ratios, the calcining temperature and time was investigated by using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and granularity analysis. It was found that at the Li / Mn mole ratios, the calcining temperature and time play an important role in the structure of the product. The results show that when the product with n(Li / Mn)=0.55 is calcined for 8h at 600 C, it exhibited standard spinel structure with the size between 40nm. The particles are fine, narrowly distributed and well crystallized.It was found that many elements doped in lithium manganese oxide could stabilize its structure, such as Ce. In this paper, LiMn2-xCex04(x=0.02,0.04,0.06) was studies in order to furture understand the dependence of the electrochemical performance on the doped rare earth metals. The cathodes are more tolerant to repeated lithium extraction and insertion than a standard LiMn2O4 spinel electrodein spite of a small reduction in the initial capacity, especial their cycling propertiesat high temperature were improved, obviously.