离子掺杂和碳修饰对Li_2FeSiO_4结构和性能的影响

Effect of Ion Doping and Carbon Modification on the Structure and Performance of Li_2FeSiO_4

采用高温固相反应方法合成锂离子电池正极Li_2Fe_(1-x-y)Mn_xNi_ySiO_4/C复合材料,并采用X-ray线衍射、扫描电子显微镜和电化学分析方法,研究了Ni和Mn离子共掺杂及碳修饰复合改性对复合材料结构和性能的影响。结果表明,复合改性没有对材料的晶体结构造成改变,镍锰离子共掺杂和表面碳包覆能有效提高材料的比容量和循环性能;以C/32倍率充放电,复合掺杂得到的Li_2Fe_(0.6)Mn_(0.2)Ni_(0.2)SiO_4/C材料样品的电化学性能最优,根据实测结果,该复合材料的首次放电比容量达到149 m Ah·g^(-1),充放电循环10次以后容量保持率仍有95.3%。

High temperature solid phase reaction method was used to synthesize the positive Li2Fe1-x-yMnxNiySiO4/C composites of Li ion battery. The methods of X-ray diffraction （XRD）, scanning electron microscope （SEM） and electro-chemical analysis method were applied to investigat the effect of Ni ＆amp; Mn co-doping and C co-modification on the composite structure and properties. The results indicated that co- modification did not change the the crystal structure of Li2FeSiO4, Ni and Mn co-doping and C-covering improved the specific capacity and cycling performance of the material, and with C/32 rate charging and discharging, the co-doping Li2Fe0.6Mn0.2Ni0.2SiO4/C exhibits the best electrochemical performance. According to the measured result, the initial discharge capacity of the composites is 149 mAh＆#183;g-1, its capacity retention ratio is still 95.3% after 10 cycles.