Study On The Hydrothermal Synthesis Of Lithium Iron Phosphate And Its Effect On Electrochemical Capacity

In this thesis, lithium iron phosphate was prepared by using FeSO4, H3PO4, and LiOH through the hydrothermal synthesis. The structure, morphology and electrochemical performance of the cathode materials were characterized by XRD, SEM and charge-discharge test. The effects of synthesis conditions on the physical characteristics and electrochemical performances of sample were investigated. SEM results showed that the synthesis temperature plays an important role in determining morphology and structure of the synthesized samples. It was found that diamond-shaped plate (LiFePO4) is formed when synthesis temperature is over130℃. However, needle-like Li3Fe2(PO4)3is formed when synthesis temperature is below130℃. Charge and discharge performance of diamond-shaped plate of lithium iron phosphate (LiFePO4) is better than the needle-like structure Li3Fe2(PO4)3. At0.1C charge and discharge rate, the first discharge capacities of needle-like structure and diamond-shaped could be up to57mA·h/g and106mA·h/g respectively. The poor capacity of3is brought by the unbalance of Fe to PO4.