LiFePO4 modified Li1.02(Co0.9Fe0.1)0.98PO4 cathodes with improved lithium storage properties

• Main Authors: Aravindan, Vanchiappan, Jang, I. C., Son, C. G., Yang, S. M. G., Lee, J. W., Cho, A. R., Park, G. J., Kang, K. S., Kim, W. S., Cho, W. I., Lee, Y. S.
• Other Authors: Energy Research Institute @ NTU (ERI@N)
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Chemistry
• Online Access: https://hdl.handle.net/10356/100183; http://hdl.handle.net/10220/24100
• Institution: Nanyang Technological University

LiCoPO4 and Li1.02(Co0.9Fe0.1)0.98PO4 were prepared by conventional solid state reactions. The surface modification of Li1.02(Co0.9Fe0.1)0.98PO4 particulates by LiFePO4 was successfully carried out by a dry coating procedure. TEM analysis confirmed the presence of a LiFePO4 coating layer of about 20 nm on the surface of the Li1.02(Co0.9Fe0.1)0.98PO4 particles. All three cells delivered high initial discharge capacities of 122, 130 and 128 mA h g−1 for LiCoPO4, Li1.02(Co0.9Fe0.1)0.98PO4, and LiFePO4 modified Li1.02(Co0.9Fe0.1)0.98PO4, respectively. However, these cells presented quite different cycle retention rates after 20 cycles, 21, 22 and 70% for LiCoPO4, Li1.02(Co0.9Fe0.1)0.98PO4, and LiFePO4 modified Li1.02(Co0.9Fe0.1)0.98PO4, respectively. The improved cycle retention of the LiFePO4-modified Li1.02(Co0.9Fe0.1)0.98PO4 resulted from its reduced reactivity towards the electrolyte and the effective prevention of resistive layer formation on the LiCoPO4 surface during high voltage cycling.