By Solid State Reaction Synthesis Of Lithium Manganese Oxide Materials And Their Electrochemical Properties Of The Test

With the development of electronic technique, high-energy-density portable powers are demanded more and more. Lithium ion secondary batteries have become attractive for portable devices due to their higher energy density and discharge-voltage, compactness and lightness compared to the other systems. Since the introduction of lithium ion batteries by SONY, the market for these batteries has grown to around 0.4 billion cells per year by the end of 2001. 95% of portable cameras, mobile telephones, handheld computers and others has been using lithium ion secondary batteries as major power supply.Every year, the most lithium ion batteries are made in Japan. The Japanese own the most patterns of such battery in the world. The corporations of our country began lithium ion batteries production more later than that of Japan. However, on the grounds of incomplete statistics, there are about 200 companies to produce lithium ion batteries.According to the same basic principles announced by SONY, which use carbon as negative electrode into which lithium ion intercalates and use a lithium cobalt oxide, LiCoO₂, as positive electrode, a vast majority of the lithium ion batteries are produced. The voltage range is 2.5-4.2V, with a nominal voltage of 3.6V. But cobalt is rather rare and it must prepare for military affairs, it is so expansive that it couldn't be acceptedby the high-power instruments. The spinel Lithium manganese oxide (LiMn2O4) has attracted because of the lower price and less toxicity advantages of manganese over cobalt. Under electric field function, the lithium ion can insert or deinsert through the stereoscopic framework which is constitute of manganese oxide. Many researchers are working hard to try to replace LiCoO2 with LiMn2O4, as will broader the application of lithium ion batteries.The spinel LiMn2O4 was prepared by low-heating temperature solid-state reaction method. The thermal analysis of the precursor was taken. XRDs TEM> XPSn ICP was used to characterize the structure, morphology and constituent of LiMn2C>4 material. And LiMn2O4 as cathode material was assembled into two or three electrode simulation cells designed by ourselves. The simulation cells were used in electrochemical performance test and many useful data were get.Whereas the poor cycle life of spinel LiMn2C>4, several kinds of anions and cations such as Li+ -, Y3\ Al3+\ Cr3+> S2^were selected to dope into the material. The result was improved just as we expect.A brief and practical formula was put forward, which can be used to calculate the theoretical capacity of the doped lithium manganese oxide and can indicate which kind of doped ions should be chosen.The behaviors of charge/discharge of spinel LiMn2O4 on several different collecting current were investigated, trying to find out a goodcurrent collector for the cathode materials of lithium ion batteries.