Synthesis And Research Of Lithium Iron Phosphate As Cathode Material

Presently Lithium Iron Phosphate (LiFePO4) has become more and more concerned for its so many obvious characters such as few toxic,environmental friendly,low raw material cost,high specific capacity,excellent cycle performance and safety ,and it is considered to be the most promising cathode material for dynamical battery. However the bad high rate performance because of the low electronic conductivity should be improved. Based on decreasing the production cost and enhancing the high rate performance of this material , this paper adopted a two-step solid-state reaction to improve LiFePO4`s behavior mainly using carbon coated or doped and Mg2+ doped method .It is found that we can more easily obtain the good behavior material under the conditions of 600℃sintering temperature,Ar/H2 inertia atmosphere ,after testing the influence of the different sintering temperature and inertia atmosphere during the reactions to the performance of LiFePO4 . The cycle performance was improved greatly through a modified high temperature solid-state method.LiFePO4/C composite was synthesized by three different carbon precursor under different sintering technology, and the sample achieved under the sintering method of 300℃/3 h+550℃/12 h and glucose as the carbon precursor exhibits a excellent electrochemical behavior , the specific capacity rised quickly to 142.0 mAh/g from the first discharge of 117.3 mAh/g just in only 7 cycles under the measuring current of 20.0 mA/g , then it keeps the capacity of nearly 140.0 mAh/g safely , and can reach 102.7 mAh/g when the current density is 200 mA/g . LiFePO4/C composite sample synthesized using coal tar bitumen and carbon both as the carbon precursor under 300℃/3 h+650℃/6 h also gives a good discharge curves ,the discharge specific capacity reached 104.0 mAh/g,100.2 mAh/g under the measuring current of 183 mA/g,366 mA/g respectively ,and it keeps the good cycle performance in nearly 140 cycles. Few reports were related to the LiFePO4/C composite synthesized using low cost bitumen as the carbon precursor. It was discovered that the carbon as the precursor has a usual effect on improving the performance of LiFePO4.The discharge capacity increases as the voltage range for charge-discharge...