还原-插锂和碳包覆同步制备磷酸铁锂/碳复合材料及其性能

以聚丙烯酸为碳源,用低温还原-插锂与聚合物高温分解相结合的方法制备LiFePO4/C复合正极材料;FePO4被还原插锂与含碳聚合物化学包覆同时进行,简化了制备工艺,降低了制备成本。经X射线粉末衍射(XRD)、扫描电镜(SEM)以及恒电流充/放电测试,研究了不同焙烧温度对合成产物的物相、晶胞参数、表面形貌及电化学性能的影响。研究发现,焙烧温度为600℃时,合成产物的0.1 C倍率放电具有最高的放电容量和最好的循环稳定性。在0.1 C下LiFePO4/C复合材料的首次放电容量高达141.3 mAh/g,库伦效率为98.0%,100次循环后,其容量保持率为108.3%。

Preparation and Performance of LiFePO4/C Composite Material via Reduction-Inserted Lithium in the Presence of Coating with Carbon

LiFePO4/C composite cathode material was prepared with polyacrylic acid as carbon source by a method combining a low temperature reduction-inserted lithium and polymer pyrolysis, in which FePO4 was reduced with lithium insertion and a simultaneous chemical coating occurred with carbon-containing polymer. The technique simplifies the preparation process and reduces the production cost. The phase structures, lattice parameters, morphologies and electrochemical properties of LiFePO4/C samples synthesized at different calcination temperatures were characterized by XRD, SEM and galvanostatic charge-discharge test. The results show that the maximum discharge capacity and best cycling stability of present products are obtained when the calcination temperature is 600 oC at 0.1C rate. The initial discharge specific capacities of resulting LiFePO4/C composite material reaches 141.3 mAh/g with a coulombic efficiency of 98.0% at 0.1C rate, and the capacity retention rate is 108.3% after 100 cycles.