(中南大学 冶金科学与工程学院， 长沙 410083)
摘 要: 采用高温固相法合成了锂离子电池正极材料LiFePO4及改性的LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C材料。 采用X射线衍射仪和扫描电镜分析样品的晶体结构和表面形貌。 结果表明： 改性后的LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C材料与LiFePO4一样均为单一的橄榄石结构。 以20 mA/g电流密度充放电， LiFe0.9Ni0.1PO4的首次放电容量为140 mA·h/g， 较LiFePO4增加了12%； 而复合掺杂得到的含碳量为2.8％的LiFe0.9Ni0.1PO4/C材料， 首次放电容量达162 mA·h/g， 充放电循环30次后放电电容量仍为147 mA·h/g， 容量衰减仅为9％。 当充放电电流密度提高到80 mA/g时， LiFePO4、 LiFe0.9Ni0.1PO4和LiFe0.9Ni0.1PO4/C的放电容量分别为86、 114和140 mA·h/g。 改性后的LiFe0.9Ni0.1PO4/C的电化学性能得到了较大的改善。
关键字: LiFePO4； Ni掺杂； 碳包覆； 电化学性能
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract: LiFePO4, LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C were synthesized by solid-state reaction and all samples were characterized by XRD, SEM and electrochemical performance. The results show that LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C are still olivine type with good electrochemical performance. When the cathode materials are cycled at 20 mA/g, the LiFe0.9Ni0.1PO4 can delivered 140 mA·h/g at the first discharge which is 12% higher than that of LiFePO4, while LiFe0.9Ni0.1PO4/C can reach 162 mA·h/g at the first discharge and only lost about 9% after 30 cycles. When the discharge current density reaches up to 80 mA/g, the capacity of LiFePO4, LiFe0.9Ni0.1PO4 and LiFe0.9Ni0.1PO4/C are 86, 114 and 140 mA·h/g, respectively.
Key words: LiFePO4; Ni doping; carbon coating; electrochemical performance
