Study On The Synthesis Of Perovatite Phosphate Cathode Materials

With the growing deterioration of global energy and resources, the development of new energy material has become the focus of worldwide attention. Lithium ion battery have drawn great attention for its high voltage, high capacity, excellent cycle performance and so on. In this paper, the development, structure and status of cathode material of lithium ion batteries were reviewed in detail. The synthesis of precursor of LiFexMn1-xPO4(x=1.0.9,07.0.5) and the carbn coated LMFP were deeply studied, and the morpholog, structure and electrochemical were showed by using XRD,SEM, Roman spectra and charge-discharge test.With the method of co-precipitation, under the ultrasonic wave, the anode material precursor ferromanganese ammonium phosphate is compounded, and it is discovered that PH plays an essential role in the process of synthesis precursor.With the increases of PH, the degree of crystallinity and orientation of the material are enhanced accordingly; its morphology of particles is gradually transformed into single sub-micron piece. As temperature increases, the size of particles comes to enlarge and the extent of reunion is fortified. The improvement of ultrasonic power helps to promote the dispersity of particles of the material. At the same time, the introduction of ultrasonic is beneficial to the formation of sub-micron piece.In the process of synthesis, this thesis paper initially studies LFP anode material covered by carbon source in variety, and finds out that composite material LFP/C prepared by glucose as carbon source, possesses the best electrochemical property which discharges the capacity of 113mAh/g in 0.2C for the first time. At the same time, it possesses favorable rate capability that discharges the capacity of 105mAh/g in 1C rate for the first time, and still discharges the capacity of 95mAh/g in a high rate of 5C. Primarily comparing the property of different iron and manganese, the the paper draws a conclusion that LiFe0.9Mn0.1PO4/C anode material mingled by a small amount of manganese, helps deintercalate of Lithium iron, with the best electrochemical property, owing to the lowering of inter-electrode polarizability. In the wake of the increase of the content of manganese, their discharge platforms tend to be obvious. However, the lowering of manganese iron conductivity results in the decline of discharge capacity. This paper investigates different roasting temperature and holding time to the effect of morphology and property of anode material. Eventually, it is discovered that on the condition of 800℃ of the roasting temperature and 10 hours of the holding time, the best anode material in electrochemical property can be obtained, discharging the capacity of 129mAh/g in 0.2C for the first time, and the anode material possesses the favorable ate capability, discharging the capacity of 114mAh/g in 1C rate for the first time,88.4% of the retention rate of capacity, still even 97.6mAh/g of the discharge capacity in a high rate of 5C.