Co掺杂LiFePO4 /C的共沉淀-微波合成及电化学性能
Electrochemical Properties of Co-doped LiFePO4 /C Prepared by Coprecipitation-microwave Method
张 勇, 杜培培, 王力臻, 张爱勤
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作者单位：(郑州轻工业学院 河南省表界面科学重点实验室, 河南 郑州 450002)
中文关键字：LiFePO4； 锂离子电池； 共沉淀-微波法； 掺杂； 电化学性能
英文关键字：LiFePO4; lithium ion batteries; coprecipitation-microwave method; doping; electrochemical properties
中文摘要：采用共沉淀-微波法制备了Co掺杂的锂离子电池正极材料LiFe1-xCoxPO4 /C(x=0.00、0.01、0.03、0.05、0.07、0.09)。研究了微波时间、柠檬酸量、掺Co量等因素对材料结构、形貌和电性能的影响。XRD、SEM和电化学测试表明：该方法制备的样品为橄榄石型非晶结构，粒径尺寸为0.5～5 μm，颗粒分布比较均匀。微波15 min、柠檬酸量为20wt%时，LiFePO4 /C电化学性能最优，0.1C倍率放电可达124 mA·h/g，第20次循环的比容量为117 mA·h/g。掺杂Co在很大程度上可以提高LiFePO4 /C的电化学性能，当Co含量为5 wt%时，LiFe0.95Co0.05PO4 /C的比容量为最大值，0.1C倍率放电可达136 mA·h/g，第20次循环的比容量为125 mA·h/g，容量保持率为91.9%。
英文摘要：Stoichiometric Co-doped lithium iron phosphates LiFe1-xCoxPO4 /C (x=0.00, 0.01, 0.03, 0.05, 0.07, 0.09) cathode materials for lithium ion batteries was synthesized by coprecipitation-microwave method. The effects of microwave time, the amount of citric acid, the content of doped cobalt on the microstructure, morphology and electrochemical properties of LiFe1-xCoxPO4 /C were analyzed. The results show that the optimal condition is: microwave time of 15 min, the amount of citric acid reaches 20wt%. Under this condition, the sample has an olivine-type amorphous structure and grain size is in the range from 0.5 μm to 5 μm. When charge-discharge at 0.1 C, its initial specific discharge capacity is 124 mA·h/g, the specific capacity at the 20th cycle is 117 mA·h/g. The content of Co is an important factor to influence the performance of LiFePO4. Charge-discharge test shows that the cathode materials with the Co content of 5wt% possess excellent charge/discharge capacities, about 136 mA·h/g at 0.1 C rate and 125 mA·h/g in the 20th cycle, the capacity retention is 91.9%.