摘要
Using low-cost FePO4·2H2O as iron source,Na2FePO4F/C composite is prepared by alcohol-assisted ball milling and solid-state reaction method.The XRD pattern of Na2FePO4F/C composite demonstrates sharp peaks,indicating high crystalline and phase purity.The SEM and TEM images reveal that diameter of the spherical-like Na2FePO4F/C particles ranges from 50 to 300 nm,and HRTEM image shows that the surface of Na2FePO4F/C composite is uniformly coated by carbon layer with a average thickness of about 3.6 nm.The carbon coating constrains the growth of the particles and effectively reduces the agglomeration of nanoparticles.Using lithium metal as anode,the composite delivers a discharge capacities of 102.8,96.4 and 90.3 mA·h/g at rates of 0.5C,1C and 2C,respectively.After 100 cycles at 0.5C,a discharge capacity of 98.9 mA·h/g is maintained with capacity retention of 96.2%.The Li+diffusion coefficient(D)of Na2FePO4F/C composite is calculated as 1.71×10^–9 cm^2/s.This study reveals that the simple solid state reaction could be a practical and effective synthetic route for the industrial production of Na2FePO4F/C material.
选用二水合磷酸铁为铁源,经乙醇辅助球磨和固相反应制备了氟磷酸亚铁钠/碳复合材料。X-射线衍射证实产品有高的结晶度和相纯度。扫描电镜和透射电镜照片显示,球形氟磷酸亚铁钠粒子的粒径分布在50~300 nm之间;从高分辨透射电镜图可以看出,在氟磷酸亚铁钠/碳复合材料的表面包覆了一层厚度为3.6 nm的碳层。碳层的包覆能有效地遏制氟磷酸亚铁钠粒子的长大及粒子的团聚。以锂片作为负极组装半电池,在0.5C,1C,2C倍率下,复合材料的放电比容量分别为102.8,96.4,90.3 mA·h/g。0.5C循环100次后电池的放电比容量为98.9 mA·h/g,容量保持率为96.2%。从循环伏安曲线计算得到氟磷酸亚铁钠/碳复合材料的锂离子扩散系数为1.71×10^–9cm^2/s。显然,固相法是制备锂离子电池正极材料用氟磷酸亚铁钠/C复合材料的有效方法。
作者
HU Hai
WANG Yu
HUANG Yan
SHU Hong-bo
WANG Xian-you
胡海;王誉;黄妍;舒洪波;王先友(School of Mechanical Engineering and School of Chemistry,Xiangtan University,Xiangtan 411105,China;National Base for International Science & Technology Cooperation,National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery,Hunan Province Key Laboratory of Electrochemical Energy Storage and Conversion,Xiangtan 411105,China)
基金
Projects(51472211,51502256)supported by the National Natural Science Foundation of China
Projects(2016GK4005,2016GK4030)supported by the Strategic New Industry of Hunan Province,China
Project(13C925)supported by the Research Foundation of Education Bureau of Hunan Province,China
