表面多孔球形LiFePO4/C的制备及其电化学性能

采用一步溶剂热法合成球形LiFePO4,并进一步在饱和葡萄糖溶液中浸泡包碳形成表面多孔球形LiFePO4/C.利用XRD、SEM、HRTEM、FTIR和BET对样品的纯度、成分、晶型、形貌和孔结构进行了表征.实验结果表明:表面多孔结构使表面多孔球形LiFePO4/C拥有更大的比表面积以及更多的活性位点,并极大缩短了锂离子在充放电过程中的迁移距离,降低锂离子在材料中扩散及脱嵌阻力;在保持较高振实密度(1.36 g·cm-3)的前提下进一步提高材料的利用率以及较大倍率下的充放电性能,使表面多孔球形LiFePO4/C拥有优良的电化学性能.

Preparation and Electrochemical Properties of LiFePO4/C Porous Spherical Microstructures

Spherical LiFePO4 was synthesized by one-step solvothermal method, and then the spherical LiFePO4/C with porous surface was formed by soaking carbon in saturated glucose solution. The purity, composition, crystal morphology and the porous structure of the cathode materials were characterized by XRD, SEM, HRTEM, FTIR, BET respectively. The experimental results showed that the porous surface structure made the porous spherical LiFePO4/C have a larger specific surface area and more active sites, which greatly reduced the migration distance of lithium ions in the process of charge and discharge and reduced the resistance of lithium ions diffusion and disintegration in the material. Under the premise of maintaining a high tap density (1.36 g·cm-3), the utilization rate of the material was further improved and the large rate charge-discharge performance of the material was larger. The electrochemical testing results showed that the spherical structured LiFePO4/C with porous surface had better electrochemical performance.