采用球磨-固相法,对 Mn 位进行 F e、Mg 共掺杂,合成锂离子电池正极材料 LiMn0．7 Fe0．3－x Mgx-PO4/C(x＝0．00,0．02,0．04,0．06).利用X射线衍射、扫描电镜对其结构和形貌进行表征；利用电池充放电测试系统和电化学工作站对其进行电化学性能测试.结果表明,LiMn0．7 Fe0．3－x Mgx PO4/C 呈现单相橄榄石结构；所得材料粒径分布均匀,在100 nm 左右.经F e、Mg共掺杂后材料综合电化学性能明显提高,其中LiMn0．7 Fe0．26 Mg0．04 PO4/C 材料的性能最佳,在0．1,0．2,0．5,1和2 C 倍率下的放电比容量分别为159．7,154．3,148．2,143．9和134．7 mAh/g,1 C 倍率下电池循环50次后的容量保持率为94．5％,倍率性能优异.
LiMn0.7Fe0.3-xMgxPO4/C(x=0.00,0.02,0.04,0.06)composites were synthesized by a solid-state re-action route via Mn-site co-substitution with Fe and Mg,and the crystal structure,morphologies and electro-chemical performance of the obtained materials were investigated by X-ray diffraction,scanning electron mi-croscopy and electrochemical measurements.The result shows the obtained samples are contributed to an olivine structure with uniform particle size range of 100nm.Fe and Mg co-substitution could remarkably enhance the electrochemical properties of LiMnPO4/C,and the LiMn0.7 Fe0.26 Mg0.04 PO4/C sample demonstrates the optimum electrochemical performance with initial discharge capacities of 159.7,154.3,148.2,143.9 and 134.7 mAh/g at 0.1,0.2,0.5,1,2 C respectively.Meanwhile,it can retain 94.5% of the initial capacity after 50 cycles at 1 C,re-vealing a stable cycling stability and exhibits an excellent rate capability.
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