Electrochemical properties of LiFePO4 thin films prepared by pulsed laser deposition
Electrochemical properties of LiFePO4 thin films prepared by pulsed laser deposition
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DOI：
10.1016/j.jpowsour.2005.03.117
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发表时间：
2005-08
影响因子：
9.2
通讯作者：
C. Yada;Y. Iriyama;S. Jeong;T. Abe;M. Inaba;Z. Ogumi
中科院分区：
文献类型：
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作者：
C. Yada;Y. Iriyama;S. Jeong;T. Abe;M. Inaba;Z. Ogumi
采用脉冲激光沉积法（PLD）制备了磷酸铁锂（LiFePO 4）薄膜电极。在氩气保护下对薄膜进行了不同温度的退火处理，研究了退火温度对薄膜电化学性能的影响。在773和873 K退火的薄膜在3.4V（相对于Li/Li+）处表现出一对氧化还原峰，这是LiFePO 4的电化学嵌/脱锂的特征。原子力显微镜（AFM）观察发现，在773 K退火的薄膜（773 K-薄膜）由厚度约为50 nm的小晶粒组成，且晶粒尺寸随退火温度的升高而增大。773 K薄膜由于晶粒尺寸小，具有较高的倍率性能，在10μA下放电容量为25 nA时的65%。而773 K膜的放电容量约为100 kJ/m2。比在873 K下退火的膜的小10%，表明在773 K下退火稍微不足以获得良好结晶的LiFePO 4。从这些结果可以得出结论，高倍率性能和容量之间的优化点将被发现在773和873 K之间。
Lithium iron phosphate (LiFePO4) thin film electrodes were prepared by pulsed laser deposition (PLD). The thin films were annealed at various temperatures under argon gas flow and the influence of annealing temperature on their electrochemical performance was studied. The thin films annealed at 773 and 873K exhibited a couple of redox peaks at 3.4V (versus Li/Li+) that are characteristics of the electrochemical lithium insertion/extraction of LiFePO4. Atomic force microscopy (AFM) observation revealed that the film annealed at 773K (773K-film) consisted of small grains with 50nm in thickness, and the grain size increased with an increase of annealing temperature. Because of its small-sized grains, the 773K-film showed high rate capability and the discharge capacity at 10μA maintained 65% of that at 25nA. However, the discharge capacity of the 773K-film was ca. 10% smaller than that of the film annealed at 873K, indicating that annealing at 773K is slightly insufficient to obtain well-crystallized LiFePO4. From these results, it was concluded that a point of optimization between high rate capability and capacity would be found between 773 and 873K.