摘要
以磷酸铁锂为正极活性材料,采用直接混合法,研究了添加质量分数为0.5%、1%和1.5%的石墨烯对锂离子电容器电化学性能的影响。利用扫描电子显微镜、X射线衍射分别对材料形貌、结构等进行了分析,并比较了掺杂不同石墨烯的电极材料恒流充放电性能和循环性能。结果表明,石墨烯是一种三维自支撑片状结构,粉末材料是独立形成的,并且不易团聚,纳米磷酸铁锂颗粒分散均匀,颗粒呈类球型状;掺杂不同量的石墨烯对磷酸铁锂本身结构几乎没有影响;掺杂1.5%石墨烯电极性能最好,高倍率5C时,放电比容量96 m Ah/g,容量保持率77%,当恢复到0.1C时,放电比容量是初始容量的95%,循环500圈后容量保持率达92%,阻抗最小,为0.366 1Ω。
With LiFePO4 as a cathode material,effects of addition of graphene at an amount of 0.5%,1.0% and 1.5% by direct mixing on the electrochemical performance of lithium-ion capacitor were investigated. The structure and morphology of materials were characterized by using scanning electron microscopy and X-ray diffraction. The constant current charging-discharging performance and cycle performance of electrode materials were analyzed by comparison of different addition of graphene. Results indicate that graphene is of self-supported three-dimensional sheet-like structure with its powder formed independently and difficult to be aggregated. The LiFeO4 nanoparticles are of spherical structure and homogenously dispersed as spheres. It is found that LiFePO4 that is doped with different amounts of graphene shows little difference in its structure,and material displays the best electrode performance when being doped with graphene at an amount of 1.5%. It exhibits a specific discharge capacity of 96 m Ah/g under 5 C,with a capacity retention rate at 77%. When recovered to 0. 1 C,the specific discharge capacity is 95% of the initial capacity. After 500 cycles,the capacity retention rate keeps at 92% and the impedance becomes the least,at 0.366 1 Ω.
出处
《矿冶工程》
CSCD
北大核心
2017年第6期142-145,共4页
Mining and Metallurgical Engineering
基金
广西科学研究与技术开发计划(桂科AA16380042
桂科攻1598008-14)
国家自然科学基金(51762006)
关键词
石墨烯
正极材料
电极材料
磷酸铁锂
锂离子电容器
电化学性能
graphene
cathode material
electrode material
LiFePO4
lithium-ion capacitor
electrochemical performance
