The Synthesis And Study Of Lithium Titanium Oxide And Iron Phosphate Precursor For Lithium Iron Phosphate

Lithium-ion battery is one of the most attractive in the field of new energy in recent years; Its growth and market share are rapidly expanding, especially in power lithium-ion battery. Not only the major lithium-ion battery manufacturing companies in the world have invested enormous human and material resources for research and development, but also the Governments of the United States, Japan and China, have also been given considerable support as a major direction for future energy development. Positive and negative electrode materials are the most important parts of the lithium-ion battery, not only its performance determines the overall performance of the battery, and its costs accounted for a large part of the cost of the entire battery. Therefore, improving its performance and reduce its cost are urgent.The lithium titanium oxide is known as "zero strain" material. Its structure is very stable during charge-discharge with a good cycle performance, and is difficult to form the SEI film, nearly100%coulombic efficiency, promising to be another anode material for lithium-ion battery. In this experiment lithium titanium oxide was synthesized by the solid phase reaction, amorphous TiO2and LiCO3as raw materials, n(Li)/n(Ti) was0.84Ingredients were sintered, respectively, at700℃,750℃and800℃for12h,16h and20h to get the product. The physical and electrochemical properties of product were investigated by partical size, charge-discharge, scanning electron microscope, and so on. The results showed the lithium titanium oxide obtained in the800℃for16h discharged (lithium intercalation)152.3mAh/g at0.1C for the first time, the first charge (delithiation) capacity reached151.3mAh/g, so the current efficiency reached99.3%, maintain the capacity of about145mAh/g, the retention rate of95%after the next20cycles.LiFePO4has been studied much more as a kind of positive material; However, the less investigation is performed on the preparation by iron scrap and phosphoric acid as raw materials. In the experiment iron scrap reacted with phosphoric acid firstly and then hydrogen peroxide was added, and FePO4·2H2O was precipitated. Then LiFePO4was prepared by the Carbothermal reduction of FePO4with the first charge capacity of159.0mAh/g and the first discharge capacity of154.5mAh/g, so the first charge and discharge current efficiency reached97.2%. After20cycles at0.1C, the charge and discharge capacity remained in153mAh/g and150mAh/g, and the retention rates are96%and97%respectively.