以廉价的硝酸铁为铁原料，通过溶胶凝胶和固相反应法制得碳包覆硅酸铁锂(Li2FeSiO4/C)正极材料，以偏钒酸铵(NH4VO3)为钒原料，按理论计算量5，10，15，20，25，30和50%制得钒替代Li2FeSiO4/C复合材料（Li2Fe1-xVxSiO4/C）. 结果表明，Li2FeSiO4/C(主相P21/n)结晶良好，基本无杂相，而Li2Fe1-xVxSiO4/C(主相P21/n)存在主要杂质偏硅酸锂和钒/铁氧化物. Li2FeSiO4/C和Li2Fe0.95V0.5SiO4/C电极C/16(室温)的首次放电比容量分别达160.9 mAh·g-1和130.8 mAh·g-1. 钒替代量的增加，无定形碳的石墨化程度增强，碳包覆量却减少. 钒替代量直接影响钒/铁氧化物的形成量，导致Li2Fe0.95V0.5SiO4/C电极电化学性能较差.
The carbon coated lithium iron silicate (Li2FeSiO4/C) composites were prepared using less expansive iron starting material of soluble ferric nitrate through sol-gel process and solid state reaction. The theoretically calculated amounts of 5, 10, 15, 20, 25, 30, and 50% of vanadium (V) were introduced using NH4VO3 to obtain V-substituted Li2FeSiO4/C composites. It was found that the pure Li2FeSiO4/C composite exhibited a good crystallinity with P21/n and nearly no impurities being detected, while the V-substituted Li2FeSiO4/C composites showed major impurities of Li2SiO3 and V3O4/Fe3O4. The discharge capacities of 160.9 mAh·g-1 and 130.8 mAh·g-1 at C/16 were obtained for the pure and 5% V-substituted Li2FeSiO4/C composites, respectively. The degree of graphitization in amorphous carbon was enhanced and the quantities of carbon coated were lowered with the increase of V-substituted amounts. The electrochemical performance of 5% V-substituted Li2FeSiO4/C composite was not improved due to the presences of impurities which were directly linked to the amounts of V substitution.
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