非整比磷酸铁锂Li_xM_(0.01)FePO_4的合成与电化学性能研究

Synthesis and electrochemical properties of non-stoichiometric Li_xM_(0.01)FePO_4

用流变相法成功地合成了分别掺杂Y和Mo的非整比磷酸铁锂(LixY0.01FePO4和LixMo0.01FePO4),并用XRD和SEM技术对其结构和形貌进行了表征,结果表明:LixY0.01FePO4和LixMo0.01FePO4仍然保持LiFePO4的晶体结构,但晶胞参数略有变化;两种晶体颗粒分布较均匀,其平均粒径分布在0.5～1.0μm范围。用电池综合测试技术,对目标产物的电化学性能进行了测试,当在低倍率下(0.05 C)充、放电时,LixY0.01FePO4和LixMo0.01FePO4材料的初始放电比容量分别为135、130 mAh/g;当在较高倍率(0.5 C)下充、放电时,两种掺杂的LiFePO4材料仍分别具有初始放电比容量为108、106 mAh/g,但LixY0.01FePO4却比LixMo0.01FePO4表现更好的循环性能。并对非整比掺杂磷酸铁锂材料的改性机理进行了分析。

Reheological phase reaction method（RPR） was used to synthesize non-stoichiometric lithium iron phosphate（LixY0.01FePO4 and LixMo0.01FePO4）.The samples were characterized by X-ray diffraction and scanning electron microscope techniques.The results show that both LixY0.01FePO4 and LixMo0.01FePO4 have the same crystal structure as that of the LiFePO4,but its cell parameters have little difference from that of LiFePO4.The electrochemical properties of both LixY0.01FePO4 and LixMo0.01FePO4 were tested by battery testing system.At a low discharging rate（0.05 C）,LiFePO4 samples doping with Y and Mo have the initial discharge specific capacities of 135,130 mAh/g;Even at a higher discharging rate（0.5 C）,both LixY0.01FePO4 and LixMo0.01FePO4 remain specific capacities of 108,106 mAh/g.Besides,the LixY0.01FePO4 have better electrochemical cycle performance than that of LixMo0.01FePO4.The reason for LixY0.01FePO4 and LixMo0.01FePO4 to behave good electrochemical properties as cathodes were discussed also.