多壁纳米碳管对磷酸铁锂正极材料热稳定性及表面形貌的影响

摘要

合成了一种新型的LiFePO4/多壁纳米碳管(MWCNTs)复合正极材料.通过MWCNTs和PPy-PEG粘结剂有机地在LiFePO4颗粒间构成三维网络导电结构,并借助SEM、TGA和高分辨裂解气相色谱,研究了LiFePO4-MWCNT正极材料的表面形貌和热稳定性.结果表明,500℃下该材料的热分解程度非常小,说明MWCNTs和PPy-PEG的复合是提高LiFePO4正极材料的热稳定性和改善表面形貌的有效途径.%A novel network composite cathode was prepared by mixing LiFePO4 particles with multiwalled carbon nanotubes (MWCNTs).LiFePO4 particles were connected by MWCNTs and a polymer binder,polypyrrole-polyethylene glycol (PPy-PEG),to form a three-dimensional network.The surface morphology and thermal stability of the LiFePO4-MWCNT/PPy-PEG composite cathode were investigated by scanning electron microscopy,thermogravimetric analysis and pyrolysis capillary gas chromatography.It was found by scanning electron microscopy that the particle size of LiFePO4 in the LiFePO4-MWCNT sample was smaller than thatof the pure LiFePO4 and the structure in the LiFePO4-MWCNT/PPy-PEG sample was more homogeneous than in the LiFePO4-MWCNT/PPy sample.Thermogravimetric analysis indicated that PPy-PEG blend polymer in combination with MWCNTs considerably improves the thermal stability of the final cathode material.Pyrolysis capillary gas chromatography measurements at 500 ℃showed a decreased thermal stability of organic species contained in the composite cathode material.The addition of MWCNTs was an effective way to increase homogeneity and thermal stability of the LiFePO4-MWCNT/PPy-PEG cathode material.