【摘要】 以碳酸锂、草酸亚铁、磷酸二氢铵、葡萄糖为原料,添加不同的过渡金属乙酸盐（乙酸锰、乙酸钴、乙酸镍、乙酸锌）,在氩气保护下采用高温固相法制备LiFePO₄/C复合材料。采用X射线衍射、扫描电子显微镜、同步热分析、恒电流充放电、电化学阻抗、循环伏安等方法研究掺杂金属离子及掺杂量对LiFePO₄/C晶体结构和电化学性能的影响。结果表明,LiFe_0.9M_0.1PO₄/C（M=Mn、Co、Ni、Zn）样品的晶体结构均与橄榄石型LiFePO₄相同。掺杂过渡金属阳离子可以提高LiFePO₄/C的还原电位,降低氧化电位,缩小氧化还原峰间距,提高化学反应的可逆性。掺杂后的样品在5C下的放电性能较好,以LiFe0.9Ni0.1PO4/C的放电容量最高,达到89mAh/g。更多还原

【Abstract】 By adding different transition metal acetates（manganese acetate,cobaltous acetate,nickel acetate,zinc acetate）,LiFePO₄/C composite materials were synthesized for lithium rechargeable batteries by high temperature solid-state reaction under the protection of argon,using Li₂CO₃,FeC₂O4·2H₂O,NH₄H₂PO₄,C₆H₁₂O₆（glucose）as raw materials.Effect of doping transition metal ions on crystal structure and performance of the sample was investigated by using X-ray diffraction,scanning electron microscopy,thermogravimetric analysis,galvanostatic charge discharge and electrochemical impedance spectroscopy,cyclic voltammetry.The results indicated that LiFe_0.9M_0.1PO₄/C（M=Mn,Co,Ni,Zn）and LiFePO₄ have the same crystal structure of olivine-style.Doping transition metal ions can increase the reduction potential of LiFePO₄/C,decrease the oxidation potential,reduce the distance between redox peaks,and improve the reversibility of the chemical reaction.The doped samples have a better discharge performance at 5C,especially LiFe_0.9Ni_0.1PO₄/C which has the highest discharge specific capacity reaching 89mAh/g.更多还原