Controlled Synthesis And Application Of Manganese Lithium Phosphate Cathode Material For Lithium Ion Batteries

The people have more neednees for new energies due to the development of technology and progress of humanity, which has been the foundation for the sustainable development of human beings. Lithium ions batteries have been new focus for people because of the high voltage, high energy density, small volum, light quality, no memory effect, no pollution and long cycle life.Olivine-type LiFePO4have been regarded as promising cathode materials for lithium ion batteries due to their high theoretical capacity, structural stability, flat charge/discharge plateaus, low cost and non-toxic. LiMnP04is another convincing candidate of the olivine families has been caused new attention. But the low electronics and ions diffusion limit the application of LiMnPO4materials. This paper is divided into two parts. In the first part, we reviewed the recent researches result of LiMnPO4materials, and mainly discuss with the relationship among the structure, morphology and electrochemical performance. And in the second part, we synthsised three different morphologies of LiMnP04via solvothermal method, at the same times explore the influencing factors for morphology and electrochemical performance of LiMnPO4materials to ensure the best synthesis craft:(1) We determine optimal PH atmosphere to synthsis spindle type LiMnP04nanoplates, meanwhicle make a conclution that urea could inhibit the two-dimensional growth of LiMnP04crystals. LiMnPO4nanopalte displayed the first discharge capacity of13mAh/g at0.05C.(2) We synthsis porous LiMnP04nanoplate via controlling the volume ratio between EG and deionized water into1:3. The aperture diameter of porous LiMnP04nanoplate is about70nm. The first discharge capacity is25.73mAh/g at0.05C. Glucose is used as carbon source to coat carbon layers in the surface of porous LiMnP04to control the carbon content maintaining about10%. On this basis, we mainly explore the effection for doping of Fe2+and the doping content in Mn site for the impact of structure and electrochemical performance of LiMnPO4materials. LiFe0.1Mn0.9PO4showed the best electrochemical performance. The first discharge capacity is52.85mAh/g at0.05C, and the capacity retention could attain94.61%via30cycles.(3) Oleic acid, EG and urea respectively are used as surfactant, solvent and structure inhibitors to synthsis3D flower-like LiMnPO4materials, which are constituted from1D nanowires. The first discharge capacity could display51.78mAh/g at0.05C after removing oleic acid on the surface of LiMnPO4via calcination.