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

Preparation and Performance of LiFePO_4/C Composite Material via Reduction-Inserted Lithium in the Presence of Coating with Carbon

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%。

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 ℃ at 0.1C rate. The initial discharge specific capacities of resulting Li Fe PO4/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.