Synthesis And Properties Of Lithium Ion Battery Anode Materials

The material of spinel lithium manganese is the most essential anode material of thesecondary lithium ion batteries because of itshigh discharge voltage, low toxicity, abundantresources in the earth. In recent years, it is believed that spinel lithium manganese has becomethe most important dynamical energy for vehicles in our daily life. An amount of researchesshows, the electrochemical properties of the material are affected by such factors as, synthesisprocess, the surface morphology and the spinel structure. But due to the dissolution of Mn andJahn-Teller effect of LiMn2O4still exist some shortcomings, high temperature performancecapacity attenuation fast lead to difficulty of the industrialization of the manganese acidlithium battery anode materials.This experiment manganese acid lithium powder prepared by high temperature solidphase method as battery positive electrode material, by doping and coated on modification,preparation of the battery when doping is through the process of preparation of LiMn2O4miserably mixed different elements, Jahn-teller effect; Coating is mainly good preparationafter LiMn2O4through LiMn2O4outer layer, add a layer of other substances is Mn3+cannotbe dissolved out, thus improve the LiMn2O4cycle performance experimentIn this experiment, the spinel-type lithium manganese oxide (LiMn2O4) prepared viasolid-phase sintering method was coated with magnesium titanium composite oxide(MgTiOx)in the presence of polyvinyl pyrrolidone (PVP) under the ultrasonic wave.And the SpinelLiMn2-xBxO4-yFy(x=0~0.2, y=0,0.05) was synthesized by doped with nonmetal elements B andF. The sample crystal structures, surface morphologies and electrochemical properties of thesample prepared were characterized by X-ray diffraction (XRD), scanning electronmicroscopy (SEM), and electrochemical analysis.The results indicated that:1. The X-ray diffractions indicated that the LiMn2O4coatedwith MgTiOxwere similar to that of the pure LiMn2O4,and they both showed sharp and highpeaks. The particles of the samples prepared with PVP did not aggregate obviously, and thesamples were coated completely and homogeneously. At charge-discharge rates of0.2C, the first discharge capacity can reach more than120mAh/g. Compared with pure LiMn2O4, thecapacity attenuation of MgTiOx-coated LiMn2O4reduced after fifty cycles, and showed goodelectrochemical performance;2. X ray diffractions demonstrated that the LiMn2O4doped withnonmetal elements B and F were similar to the pure LiMn2O4,and they both showed sharpand high peaks.It was shown that the cycle ability of LiBxMn2-xO4was enhanced by thedoping of B, but the first discharge capacity only can reach102.3mAh/g. first dischargecapacity of the LiMn2-xBxO4-yFyincreased to110.9mAh/g with the capacity retentions of83.14%after fifty cycles. It was shown that B and F doping can enhance the stability andcycling behavior of LiMn2O4and showed good electrochemical performance.3. LiMn2O4using a variety of methods for modification by complex ways to effectively improve theelectrochemical performance of LiMn2O4.