高倍率性能磷酸亚铁锂/碳正极材料的制备与表征

Preparation and characterization of LiFePO4/C cathode materials with high-rate performance

  • 摘要: 以水溶性酚醛树脂为碳源, Li2CO3为锂源, 纳米FePO4前躯体为铁源和磷源, 以水为介质, 采用湿法研磨混合均匀, 然后通过高温固相法制备出纳米磷酸亚铁锂/碳(LiFePO4/C)复合材料。采用XRD、SEM、TEM、TG和拉曼光谱对该复合材料进行了表征, 并研究了其电化学性能。结果表明, 制备的LiFePO4/C纳米颗粒为类球形, 表面均匀地包覆了一层约5 nm厚的碳层, 作为锂离子电池正极材料表现出良好的倍率性能和循环性能, 在0.2 C(1 C=170 mAh·g-1)、0.5 C、1 C、2 C、5 C、10 C下首次放电容量分别为151、150、146、142、132、119 mAh·g-1, 20 C下的首次放电容量也达105 mAh·g-1, 且循环50次几乎无衰减。

     

    Abstract: The nano-LiFePO4/C composites were prepared by means of wet grinding and following high temperature solid-state reaction using water-soluble phenolic resin, Li2CO3, and nano-FePO4 as precursors. The composites were characterized by XRD, SEM, TEM, TG and Raman spectroscopy and their electrochemical performances were studied. The results show that the as-prepared LiFePO4/C nano-composites are spherical-like particles which consist of a carbon shell with a thickness of about 5 nm and the LiFePO4 core, and show excellent high-rate performance and cycling performance as the cathode for lithium ion batteries. The initial discharge capacities at rates of 0.2 C (1 C=170 mAh·g-1), 0.5 C、1 C、2 C、5 C and 10 C are 151 mAh·g-1, 150 mAh·g-1, 146 mAh·g-1, 142 mAh·g-1, 132 mAh·g-1 and 119 mAh·g-1, respectively. The material still shows initial discharge capacity of 105 mAh·g-1 even at 20 C and its capacity doesn’t decay after 50 cycles.

     

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