F-doped lithium iron phosphates were synthesized and in~situ carbon coated by two-step solid-state reaction using Fe(Ⅲ) compound as the iron source and polypropylene as the reductive agent and carbon source. The results show that the synthesized powders are near-spherical particles of 50--200nm with the olivine type LiFePO4 structure. Two-step solid-state reaction inhibits the growth of LiFePO4 particles more efficient compared with one-step solid-state reaction. The results of electrochemical measurement show that fluorin doping improves the rate capability of LiFePO4 and decreases the polarization of LiFePO4 electrode effectively. The discharge capacities of LiFePO3.98F0.02/C cathode material are 146mAh/g, 137mAh/g, 122mAh/g at charge and discharge rates of 1C, 2C, 3C, respectively. Cycling efficiency of 99.3% can be obtained after 55 cycles at 1C rate.
ZHOU Xin
,
ZHAO Xin-Bing
,
YU Hong-Ming
,
HU Jie-Zi
. Electrochemical Properties of F-doped LiFePO4/C Prepared by Solid-state Synthesis[J]. Journal of Inorganic Materials, 2008
, 23(3)
: 587
-591
.
DOI: 10.3724/SP.J.1077.2008.00587
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