Metal Phthalocyanine Research On Lithium-ion Battery Cathode Material LiFePO _{4 Modified And Performance}

With the development of the automobile industry, serious environment pollution problem has been caused by the fuel. Lithium-ion battery, as one of the most potential alternative petrochemical energy power, has attracted widespread attention. Among so many hot researched cathode materials, lithium iron phosphates (LiFePO4) with an olivine structure is regarded as an excellent candidate for lithium ion battery cathode materials because of its high theoretical capacity, low cost, abundant resources, environmental benignity, and good thermal stability. Currently, LiFePO4material has been widely used in many fields, such as portable electronic products and electric vehicles. Unfortunately, low electronic conductivity and slow diffusion of Li+in LiFePO4greatly hold it back from large scale applications in the field of power battery.Carbon coating is regarded as the most effective way to improve electrochemical properties of LiFePO4materials, and the type and structure of carbon sources tremendously impact the performance of LiFePO4. Metal phthalocyanine has great potentials on the battery application, which makes them become one of research hotspots in the field of electrochemistry. Metal phthalocyanines not only contain metals but also can produce pyrolytic carbon, while other compounds do not possess both advantages simultaneously. There is no literature reported metal phthalocyanine used as carbon source precursor on modification of LiFePO4so far. In this paper, by combining solvothermal methods with high temperature calcination in preparation of LiFePO4/C material, transition metal phthalocyanine is selected to modify LiFePO4, which have prospect to make actual capacity of lithium battery much closer to theoretical capacity, and can be better applied in industral battery.Among synthesized LiFePO/C materials, LiFePO4/C-12exhibits remarkable electrochemical performance. The first discharge specific capacity of the battery used LiFePO4/C-12was achieved as high as150.7mAh·g-1which is close to the theoretical capacity. The discharge capacity of the battery was still at high level of127.6mAh·g-1after50cycles which is higher than that of the battery used the pure LiFePO4material (106.6mAh·g-1). Since LiFePO4/C composite has favourable electrochemical properties, it is suitable for high power battery in the applications of industrial lithium ion battery, and has great significance to the development of electric vehicles.