표면 비정질 층에 의한 LiFePO4 양극활물질의 전기화학적 특성향상

Abstract

The storage of electrical energy at high charge and discharge rate is an important technology in today's society and can enable hybrid and plug-in hybrid electric vehicles. Recently, LiFePO4 has been extensively investigated by many researchers because it's has some merits such as less inexpensive, less toxic and good thermal property. Although it has advantage, but utilization as a cathode material in lithium secondary battery is limited by its low ion mobility and low electronic conductivity. In this search, we have tried to overcome this drawback of LiFePO4 by carbon coating and low temperture heating treatment produced a surface amorphous layer. amorphous. This LiFePO4 material has high mobility of Li-ions in the bulk. The LiFePO4 was synthesized by using the starting materials such as Li2CO3, FeC2O4․2H2O, and (NH4)2HPO4. Which synthesized by mechanical alloying process and following heat-treatment. Their structures were investigated by synchrotron XRD and particle morphologies of these materials were observed by SEM and TEM. Half cells with lithium metal as a countor electrode were assembled for measuring electrochemical properties. Cycling performance of the heat treated LiFe0.9P0.95O4-？？/C at 600？？ for 10h initial discharge capacity was 135 mAh/g, which was lower discharge capacity to 106 mAh/g after 100 cycles. But, Seed350-10% (LiFePO4, heat treated at 350？？ for 10h, 10wt%) has initial discharge capacity was 145 mAh/g, which rose up discharge capacity to 152 mAh/g after 100 cycles.