LiFePO4／C复合正极材料的固相法合成

Solid-reaction Synthesis of Composite Cathode Materials LiFePO_4/C

以LiOH.H2O、FeC2O4.2H2O、NH4H2PO4和C6H12O6.H2O为原料,采用一步固相法在氮气氛下合成了LiFePO4/C复合正极材料。采用XRD、SEM和电池性能测试仪对合成产物进行了表征。研究了煅烧温度、煅烧时间、葡萄糖用量和锂过量对合成产物结构和电化学性能的影响。实验结果表明,采用一步固相法合成LiFe-PO4/C的最佳条件为:将经过高能球磨的前驱体在氮气氛下于650℃煅烧18h,葡萄糖用量为其它原料总质量的10%,锂过量10%(摩尔分数)。在此条件下合成的LiFePO4/C具有单一的橄榄石型结构和良好的电化学性能,0.1C的首次放电容量达到154.87mAh/g,30次循环后放电容量仍保持138.97mAh/g。

The composite cathode material LiFePO4/C for lithium-ion batteries was synthesized via solid-reaction in nitrogen atmosphere using LiOH· H2O, FeC2O4 · 2H2O, NH4H2PO4 and C6H12O6 · H2O as starting materials. The structure, morphology and electrochemical performance of the synthesized products were characterized by XRD, SEM and BTS, respectively. The effects of calcination temperature and time, the amount of glucose and excess lithium on the structure and electrochemical performance of synthesized products were investigated. The optimum conditions to synthesized LiFePO4/C by solid-reaction are： to calcine the high-power-milled precursor at 650℃ for 18h in nitrogen, the amount of glucose being 10% of the total amount of other raw materials, the excess lithium being 10mol%. The LiFePO4/C synthesized under such conditions has a single olive crystal structure and excellent electrochemical performance, its 0. 1C discharge capacity is up to 154. 87mAh/g at first cycle, and retains 138. 97mAh/g at the 30th cycle.