利用碳热还原法制备了LiFePO4/C 以及 Zn掺杂的 LiFePO4/C. 通过X射线衍射、扫描电镜、透射电镜、恒流充放电、循环伏安法等手段对其物化性质进行了分析. 结果表明: 少量Zn掺杂不改变LiFePO4的晶体结构. 在充放电过程中, Zn2+可以减少晶体体积收缩, 为锂离子的扩散提供较大的空间, 使其充放电性能特别是较高倍率下的循环特性得到提高.
Alien atom doping has been adopted to modify the electrochemical performance of olivine type LiFePO4 for cathode material. Here, we report that zinc-doping can improve the performance of LiFePO4/C immensely by a simple method. LiFePO4/C and Zn-doped LiFePO4/C cathode materials were firstly synthesized by carbothermal reduction method. Physical-chemical characterizations were done by X-ray diffraction, scanning electron microscope and transmittance electron microscope. Electrochemical behavior of the cathode materials were analyzed by using cyclic voltammetry, and galvanostatic measurements were employed to characterize the reaction of lithium ion insertion and de-insertion. ICP and XRD analyses indicate that Zn ions were sufficiently doped in LiFePO4 and did not alter its crystal structure. During de-intercalation and intercalation process of lithium ions, the doped zinc atoms protect the LiFePO4 crystal from shrink. Consequently, the conductivity is enhanced after doping. It is noted that zinc ions doping can improve performance of LiFePO4, especially on the aspect of stable cycle-life at higher C rate.
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