离子电导率
扩散
电化学
碳纤维
阴极
离子
电导率
离子键合
材料科学
分析化学(期刊)
化学工程
化学
聚乙二醇
电极
电解质
复合材料
复合数
物理化学
热力学
色谱法
有机化学
工程类
物理
作者
Xiaoyong Yang,Jiguo Tu,Min Lei,Zicheng Zuo,Borong Wu,Henghui Zhou
标识
DOI:10.1016/j.electacta.2016.02.068
摘要
Secondary LiFePO4/C microspheres (LFP) are synthesized with different carbon sources by the spray drying process. The carbon sources effect on the structures, morphologies, and 3D conductivity of the secondary structure are systematically investigated. LFP samples prepared with polyethylene glycol (PEG) and beta-cyclodextrin (β-CD) as mixing carbon sources possesses the loose structure with higher specific surface area, showing the best rate capability, cycling stability and low-temperature discharge characteristic. Additionally, the differences of 3.3 V plateau performance at room temperature and 2.85 V plateau performance at −20 °C are investigated. It could be observed that the electronic and ionic conductivities are reduced gradually with the decrease of the discharge cut-off voltage, while the electronic conductivities are greater than ionic conductivities for the four LFP samples, indicating that the ionic transport is more difficult and the electrochemical reaction is more and more difficult with the increase of Li-ion intercalation. Li-ion diffusion coefficients at the cut-off voltage of 3.30 V under room temperature and at the cut-off voltage of 2.85 V under −20 °C are both the highest for the LFP sample synthesized with PEG and β-CD, further indicating that PEG and β-CD as mixing carbon sources can decrease the charge transfer resistance and promote the 3D electronic/ionic conductivities and Li-ion diffusion coefficients in the secondary structure, thus greatly improve the rate capability, cycling stability and low-temperature capacity of LFP cathode.
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