不同碳源的溶胶-凝胶法制备LiFePO_4/C正极材料

以聚乙二醇、乙炔黑、甘氨酸、葡萄糖作为不同碳源,采用溶胶-凝胶法制备LiFePO_4/C复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)、热重分析等分别对合成产物进行表征,用恒电流充放电测试分析了LiFePO_4/C样品的电化学性能。结果表明,引入碳源所制得的材料具有单一的橄榄石型晶体结构,与纯相LiFePO_4相比,以甘氨酸为碳源和络合剂制备的LiFePO_4/C具有更小的颗粒尺寸和优异的电化学性能。样品的平均颗粒尺寸在1.7μm并且分布均匀,在0.2 C下首次放电比容量有163.5 m Ah/g。在0.5 C、1 C下循环20次后比容量分别保持为130.1和112.3 m Ah/g,循环稳定性优异。

Synthesis of LiFePO4/C cathode material by different carbon source assisted sol-gel method

To improve the performance of LiFePO4,LiFePO4/C composite cathode materials were synthesized by sol-gel method using carbon source such as PEG,acetylene black,glycine,glucose respectively.The precursors and the products of LiFePO4/C were characterized by XRD,SEM,thermal analysis and electrochemical performance test.The results show that the LiFePO4/C composite material synthesized using carbon source has a simple pure olive-type phase;compared with pure phase LiFePO4,LiFePO4/C synthesized with glycine has much smaller particle size and superior electrochemical performance;the average particle size of LiFePO4/C material is 1.7 μm and uniform distribution;the initial discharge capacity is achieved to 163.5 mAh/g at 0.2 C.It retains discharge spaecific capacity of 130.1 mAh/g and 112.3 mAh/g at 0.5 C and 1 C after 20 cycles.The sample exhibits good electrochemical performance and high cyclic stability.