Impact of the carbon coating thickness on the electrochemical performance of LiFePO4/C composites
Impact of the carbon coating thickness on the electrochemical performance of LiFePO4/C composites
复制标题
DOI：
10.1149/1.1860492
复制
发表时间：
2005-01-01
影响因子：
3.9
通讯作者：
Jamnik, J
中科院分区：
文献类型：
--
作者：
Dominko, R;Bele, M;Jamnik, J
采用溶胶凝胶法制备了具有不同碳量的多孔、结晶良好的LiFePO4/C复合材料。用高分辨率电子显微镜测定了碳涂层(画)的厚度。结果表明，碳涂层厚度可以由碳量控制，并对所获得的可逆容量有影响。此外，研究还表明，在合成的LiFePO4/C复合材料中，非活性Fe(III)相(可能是Fe3P)的原子比取决于复合材料中的碳含量。用穆斯堡尔谱证实了在循环过程中非活性Fe(III)在复合材料中几乎保持不变。以柠檬酸根离子为凝胶剂制备的LiFePO4/C复合材料的最低含碳量为3.2wt%，相当于碳涂层厚度约为1-2 nm。在室温下，电流密度为170 mA/g(C/1比)时，由上述复合材料获得的可逆容量接近理论容量的80%。(C)2005年电化学会。[DOI：10.1149/1.1860492]版权所有。
Porous, well crystalline LiFePO4 /C Composites with different amounts of carbon have been prepared by a sol-gel technique. The thickness of carbon coatings (paintings) has been determined by high-resolution transmission electron microscopy. It is shown that carbon coating thickness can be controlled by the amount of carbon and it has an impact on the obtained reversible capacity. Furthermore, it is shown that atomic ratio of nonactive Fe(III) phase (presumably Fe3P) in as-synthesized LiFePO4 /C composites depends on the amount of carbon in the composite. Using Mossbauer spectroscopy, we have confirmed that the nonactive, Fe(III) remains nearly unchanged in the composite during cycling. The lowest amount of carbon in LiFePO4 /C composites obtained from citrate anion as a gelling agent was 3.2 wt % and this particular amount corresponds to the carbon coating thickness of about 1-2 nm. The reversible capacity obtained from the above-mentioned composite delivers close to 80% of the theoretical capacity at room temperature with a current density of 170 mA/g (C/1 rate). (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.1860492] All rights reserved.