Polypyrrole-coated LiCoO2 nanocomposite with enhanced electrochemical properties at high voltage for lithium-ion batteries
Polypyrrole-coated LiCoO2 nanocomposite with enhanced electrochemical properties at high voltage for lithium-ion batteries
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DOI：
10.1016/j.jpowsour.2015.01.174
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发表时间：
2015-05
影响因子：
9.2
通讯作者：
Jingchao Cao;Guo-rong Hu;Zhongdong Peng;K. Du;Yanbing Cao
中科院分区：
文献类型：
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作者：
Jingchao Cao;Guo-rong Hu;Zhongdong Peng;K. Du;Yanbing Cao
采用简单的化学聚合方法在LiCoO 2表面成功地制备了导电聚吡咯薄膜。采用X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等技术对LiCoO 2和PPy包覆LiCoO 2的结构和形貌进行了研究。能量色散X射线光谱（EDXS）、傅里叶变换红外光谱（FTIR）和热重分析（TGA）进一步证明了PPy的存在。通过恒流充放电测试和交流阻抗测试研究了复合材料的电化学性能，结果表明，PPy导电膜的存在显著降低了LiCoO 2的电荷转移电阻。PPy包覆的LiCoO 2表现出良好的电化学性能，首次放电容量为182 mAh g− 1，170次循环后保留率为94.3%。然而，原始LiCoO 2的保留率仅为83.5%。倍率性能测试结果表明，包覆PPy后LiCoO 2的可逆容量保持率（10 C/0.2C）由包覆前的52.4%提高到包覆后的80.1%。连续包覆的PPy薄膜就像一个胶囊壳，它可以保护核心（LiCoO 2）免受HF的侵蚀，并大大减少了Co在电解液中的溶解。
A conducting polypyrrole thin film is successfully coated onto the surface of LiCoO2by a simple chemical polymerization method. The structure and morphology of pristine LiCoO2and PPy-coated LiCoO2are investigated by the techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Energy dispersive X-ray spectroscopy (EDXS), Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA) further demonstrate the existence of PPy. The electrochemical properties of the composites are investigated by galvanostatic charge–discharge test and AC impedance measurements, which show that the conductive PPy film on the surface significantly decrease the charge-transfer resistance of LiCoO2. The PPy-coated LiCoO2exhibits a good electrochemical performance, showing initial discharge capacity of 182 mAh g−1and retains 94.3% after 170 cycles. However, the retention of pristine LiCoO2is only 83.5%. The rate capability results show that the reversible capacity retention (10C/0.2C) of LiCoO2increases from 52.4% to 80.1% after being coated with PPy. The continuously coated thin PPy film is just like a capsule shell, which can protect the core (LiCoO2) from corrosion causing by the HF attacking and greatly reduce the dissolution of Co into electrolyte.