Synthesis And Performance Research Of Cathode Material LiMn₂O₄ Inserting Cr

Since the co modification of lithium ion battery, the most common anode material we use is LiCoO2, but because of the high price, limited resources and polluted environment, it is necessary to find a material as a substitute for LiCoO2. We have two choices, LiNiO2 and LiMn2O4, the synthetic condition of LiNiO2 is difficult to be controlled and industrialized. Compared to the compound LiCoO2 and LiNiO2, spinel LiMn2O4 is one of the most promising cathode materials for use in lithium ion batteries because of its low cost and acceptable environmental characteristics. However, it can exhibit significant capacity fading and poor cyclity during cycling, which prevent it from being commerced. Most researchers show that it results from the solution of Mn, the Jahn-Teller effect, the decomposion of organic-based electrolyte and the formation of SEM. In this paper, the inserted situation of anion and cation, and the syntheses of LiCrXMn2-XO4 are discussed comprehensively. We improve electrochemistry properties of LiMn2O4 by solid-step-method and pre-process method.This paper puts forward the pre-process method based on traditional solid-state-method, which can cut defects of solid-state-method such as the maldistribution of particle size and time-killing, etc., and the pre-process method is put forward through themogravimetic analysis and XRD technology. In our opinion, the pre-process method can synthesize the spinel LiCrXMn2-XO4 more perfect crystal shape and better electrochemistry performance than the solid-step-method.The spinel lithium manganese oxides were prepared with lithium carbonate, electrolytic manganese dioxide and chromic oxide, adding different amount of chromium. The experimental results show that adding a small amount of chromium can improve cycling performance of lithium manganese obviously, and impurity substance can be created when theamount of adding chromium reach the definite number. The spinel structure of LiCrxMn2-xO4 compounded by pre-process method is obvious, and the particle is uniform, and the initial capacity and cycling property are pretty good, more over, the battery has a 4.2V-discharge plateau, probably because chromium inletting in the spinel and perfect spinel structure result that it improves the charge-discharge performances at high voltage zone.This paper utilizes XRD, SEM, etc. technology for structural analysis of LiCrxMn2-xO4 and performance test. In addition, we explored several factors, such as composite temperature, composite time, different sources of lithium, heating up speed, different solvent of pre-process. and the impact they imposed to material capability. And then, we get the optimum synthetic condition of the experiment.