过渡金属离子掺杂对磷酸铁锂性能的影响

发布时间：2018-10-17 19:59

【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LiFePO_4/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LiFePO_4/C晶体结构和电化学性能的影响。结果表明,LiFe_(0.9)M_(0.1)PO_4/C(M=Mn、Co、Ni、Zn)样品的晶体结构均与橄榄石型LiFePO_4相同。掺杂过渡金属阳离子可以提高LiFePO_4/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。
[Abstract]:Using lithium carbonate, ferrous oxalate, ammonium dihydrogen phosphate and glucose as raw materials and adding different transition metal acetate salts (manganese acetate, cobalt acetate, nickel acetate, zinc acetate), LiFePO_4/C composites were prepared by high temperature solid state method under the protection of argon. X-ray diffraction, scanning electron microscopy, simultaneous thermal analysis, constant current charge and discharge, electrochemical impedance and cyclic voltammetry were used to study the effects of doping metal ions and doping amount on the structure and electrochemical properties of LiFePO_4/C crystal. The results show that the crystal structure of LiFe_ _ (0.9) M _ (0.1) PO_4/C (M _ (mn) Co _ (0. 1) PO_4/C) is the same as that of olivine type LiFePO_4. Doping transition metal cations can increase the reduction potential of LiFePO_4/C, reduce the oxidation potential, reduce the interval between the redox peaks, and improve the reversibility of chemical reaction. The doped samples have better discharge performance at 5C, and the discharge capacity of LiFe0.9Ni0.1PO4/C is the highest, reaching 89mAh/ g.
【作者单位】：广西大学物理科学与工程技术学院广西高校新能源材料及相关技术重点实验室;
【基金】：国家自然科学基金(61264006) 广西自然科学基金(2014GXNSFAA118340);广西自然科学基金杰出青年基金(2013GXNSFGA019007)
【分类号】：TM912

【相似文献】