Zr4+离子掺杂对LiFePO4结构及电化学性能的影响

应用固相反应法于惰性气氛下合成掺Zr的L iFePO4正极材料.考察Zr4+掺杂浓度对于目标化合物结构及其电化学性能的影响.XRD,交流阻抗和恒流充放电测试等实验表明,少量的Zr4+掺杂并未影响目标材料产物的结构,反而有利于降低L iFePO4电荷转移反应的阻抗,从而有利于克服该电极过程中的动力学限制.该正极材料表现出优良的倍率放电性能,在0.1C倍率下,L i0.99Zr0.01FePO4的首次放电比容量达135.6mAh.g-1.30次循环后,容量衰减仅3.8%.

Effects on the Structure and Electrochemical Performance of LiFePO4 by Zr4+ Doping

Stoichiometric Zr-doped lithium iron phosphate(LiFePO_(4)) cathode material was synthesized by a solid-state reaction in an inert atmosphere.The effects of doping content on the physical and electrochemical properties of as-synthesized cathode materials were investigated.The samples were characterized by powder X-ray diffraction(XRD),and their electrochemical performance was systematically measured by impedance response and constant current charge/discharge cycling tests.The results indicate that the low concentration Zr~(4 )doping does not affect the structure of the material but considerably improves its kinetics in terms of capacity delivery and cycle performance.At 0.1C discharging rate,the reversible specific capacities of the Li_(0.99)Zr_(0.01)FePO_(4)cathode material is 135.6mAh g~(-1).After 30 cycles,the capacity fade was only 3.8%.The cathode material also displays a better rate performance.