Study On The Improving Performance Of LiFePO₄ By Doping Mg And Mn

Because of its high theoretical capacity (170mAh/g),and feasible voltage (about 3.5V, vs. Li⁺/Li), good stability both at room temperature and high temperature, and being environmental benign and inexpensive, LiFePO₄ is very hopeful material as positive electrode materials for the future lithium-ion batteries material. However, it has a extremely low electronic conductivity and slow Li+ ion diffusion, and it has the poor terms of rate discharge. These drawbacks limit its large-scale application of power battery. So from LiFePO₄ emergence, the hotspot of LiFePO₄ is straight improving the electrical conductivity.The effects of technical conditions (Li/Fe ratio; sintering temperature; sintering time) on were investigated. On this basis, doping Mg²⁺,Mn²⁺ metal ions improves electrochemical performance of LiFePO₄. Charge-discharge test and XRD diffraction analysis were applied to test its performance. The results showed that : The electrochemical performance of LiFePO₄ sample which prepared at 700℃for 10h and Li/Fe(1:1). The initial discharge specific capacity is 117.39 mAh/g.LiFePO₄ is doped by Mg²⁺,Mn²⁺( each half of the 4%,6%,8%)on the location of Li or Fe or Li/Fe. The results showed that:LiFePO₄ samples which doped Mg²⁺and Mn²⁺ are simple pure olive-type phase and its electrochemical performance have significant improvement. The initial discharge specific capacity of LiFe_0.92Mg_0.04Mn_0.04PO₄ sample is 153.31 mAh/g and is better than the other samples.