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Olivine structure LiFe1−xVxPO4/C (x = 0.02, 0.04, 0.06) composite materials as the cathode for lithium ion batteries were synthesized by carbon-thermal reduction method, using Fe(NO3)3 · 9H2O, LiH2PO4, NH4VO3, and C6H12O6 (glucose) as raw materials. The X-ray diffraction (XRD), scanning electronic microscope (SEM) laser particle size analysis, specific surface area tester, and electrochemical performance testing were used to study its structure, morphology, and electrochemical properties. The results showed that the diffraction peaks of the prepared materials correspond to the single phase of LiFePO4/C and can be indexed as the olivine structure. Particle diameter of LiFe1−xVxPO4/C (x = 0.04) was uniform. Specific surface areas of materials are all increased. An electrochemical test showed that LiFe1−xVxPO4/C (x = 0.04) demonstrated a better electrochemical capacity of 141.065 mAh · g−1 at 0.1C rate, and which had an increase of 10.77% than the un-doped sample. After 20 cycles, charge and discharge specific capacity almost had no attenuation. [ABSTRACT FROM AUTHOR]

LiFe(PO4)1–xFx/C was successfully composited using a mechanical activation-carbon thermal reduction process using LiF as the doped fluoride source, andxwas 0.01, 0.02, 0.03, 0.04. In this article, material testing used scanning electron microscopy, X-ray crystal diffraction analysis, specific surface area analysis, cyclic voltammograms, and the ac impedance test. The results showed that whenx = 0.03, LiFe(PO4)0.97F0.03/C material showed good capability in regard to charge and discharge, and cycle performance was good. The specific surface area was 84.27 m2/g, which was created by the mechanical activation-carbon thermal reduction process. The initial discharge of LiFePO4synthesized under such conditions was 153.278 mA h/g (0.1C and 2.5–4.2 V). Compared with less doped LiFePO4/C material, the discharge-specific capacity of the material was 127.351 mA h/g under the same conditions. This increases by 20.34% for the initial time cycle, and after 20 circulations, the capacity was 151.512 mA h/g. [ABSTRACT FROM PUBLISHER]