摘要
采用机械液相活化法与高温固相法相结合制备了锂离子电池正极材料LiFePO4和LiFePO4/C。考察了蔗糖、柠檬酸、葡萄糖、酒石酸等不同碳源对材料性能的影响,并采用XRD、SEM和恒电流充放电测试等方法对材料的结构、表面形貌及电化学性能进行了研究,利用Raman光谱和TEM分析材料中碳的存在状态。结果表明,得到的样品结构均为橄榄石型,碳源的加入能有效地减小材料的颗粒尺寸,并且材料的电导率比纯LiFePO4的电导率提高了5个数量级。LiFePO4/C样品的表面包覆层均为非晶碳,以柠檬酸为碳源合成的LiFePO4/C材料,具有较小的颗粒尺寸,均匀多孔的表面碳包覆层和最佳的电化学性能。在0.1C下第3次的放电比容量达141.0mAh/g,循环10次后容量无衰减。
LiFePO4 and LiFePO4/C cathode materials were synthesized by a solid-state method with a mechanical activation process. The influence of different carbon sources, such as sucrose, citric acid, glucose and tartaric acid on the performances of the material was investigated. The structure, morphology and electrochemical properties of LiFePO4/C were analyzed by XRD, SEM and galvano static charge-discharge method, state of carbon coating was studied by Raman spectra and TEM. The results show that all the samples have the olivine structure, with the additive carbon source, the particle size was reduced and the electronic conductivity was improved by a factor of about 105. The carbon coatings of LiFePO4/C samples are amorphous. The sample used citric acid as the carbon source, with fine particle size and uniformly porous carbon coating, showed excellent electrochemical performances, the third discharge capacity of 141. OmAh/g under 0. 1C was obtained with no capacity fading over 10 cycles.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2008年第7期1154-1157,共4页
Journal of Functional Materials
基金
国家自然科学基金资助项目(50474092)
深圳市科技计划资助项目(200505)
关键词
正极材料
LIFEPO4/C复合材料
碳源
碳包覆
电化学性能
cathode material
LiFePO4/C composite material
carbon source
carbon coating
electrochemical per formance
