包覆碳对LiFePO4正极材料性能的影响

采用二步固相法在750℃、24h的条件下合成了纯相的和包覆碳的LiFePO4锂离子正极材料，研究了包覆碳对材料性能的影响，并结合XRD、SEM和充放电测试等手段对合成材料的结构、形貌和电化学性能进行了分析。实验结果表明：LiFePO4／C正极材料具有更小的粒径和更紧密的颗粒分布，其中包覆碳为5％的材料电化学性能最好，首次放电比容量有129．6mAh／g，分别以0．2mA和1．0mA的电流充放电循环10次后其比容量保持在120．7mAh／g和92．0mAh／g，保持率分别达100．9％和95．2％。

Effect of Carbon Coatings on the Properties of LiFePO_4 as Cathode Material

The pure LiFePO4 and carbon - coated LiFePO4 as lithium - ion cathode materials were synthesized by two - step solid - state method for 24 h at 750 ℃ to research the effect of carbon coatings on the properties of materials. The samples were characterized by X- ray diffraction, scanning electro microscope and electrochemical charge and discharge tests. These results showed that the LiFePO4 samples of adding carbon possessed smaller particle size and closer particle distribution. When adding 5 wt. % carbon, the sample has an excellent electrochemical performance with a first discharge capacity of about 129.6 mAh/g, and the discharge capacities were 120.7 mAh/ g and 92.0 mAh/g after 10 cycles at 0.2 mA and 1.0 mA charge- discharge currents respectively, then the capacity keeping percents were 100.9% and 95.2%, respectively.