Ni^2+掺杂对LiFePO_4正极材料电化学性能的影响

采用固相反应法在惰性气氛下合成了橄榄石型LiFePO4及其Ni^2＋掺杂正极材料，采用XRD，SEM和充放电等方法对目标材料进行了表征。XRD分析表明，掺杂少量Ni^2＋后的LiFePO4晶体结构并未发生变化；SEM观察发现，掺杂后，样品的粒径变小；充放电测试得出，比未掺杂的LiFePO4具有更好的电化学性能，首次放电比容量达145mAh·g^-1，高于纯的LiFePO4正极材料的容量90mAh·g^-1，经100次循环后掺杂Ni^2＋的LiFePO4和LiFePO4样品的容量保有率分别为91％和53％。

Influence of the Ni-Doped on the Electrochemical Performance of LiFePO4

Abstract： Olivine LiFePO4 and Ni^2＋ -doped LiFePO4 cathode material was synthesized by a solid state method in an inert atmosphere. The crystal stucture and electrochemical performance were characterized by XRD, SEM and electrochemical performance test. The electrochemical characterizations of LiFePO4 and Ni^2＋-doped LiFePO4 at the same technical conditions were measured. The particles of Ni^2＋-doped LiFePO4 have smaller size than LiFePO4＇ s. The addition of small numbers of Ni^2＋ had no effect on the structure of lithium iron phosphate while the cathode material showed better electrochemical performance. The initial discharge capacity of the sample as a lithium secondary battery was achieved to 145 mAh·g^-1 at 0.1 C （corresponding to 17 mAh·g^-1） , larger than that of the LiFeP04 （90 mAh·g^-1）. After 100 cycles, the capacity retention rate of LiFePO4 and Ni^2＋ -doped LiFePO4 are respect to 91% and 53%.