Ag-TiO_2-MnO_2复合材料的制备与电化学性能研究

Preparation and Electrochemical Performance of Ag-TiO_2-MnO_2 Composites

采用高温固相法制备了Ag-TiO_2共修饰的二氧化锰锂电池阴极材料,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、傅立叶红外光谱(FT-IR)、X射线光电子能谱(XPS)、能量散射X射线能谱(EDS)、循环伏安测试(CV)、恒流放电测试、交流阻抗测试(EIS)等分别检测了所制备样品的物理-化学特性及相应的电化学性能特征.结果表明,空白二氧化锰与修饰后二氧化锰均为β晶型,相比于未修饰样品,Ag-TiO_2-MnO_2样品的形貌得到了明显的改变.修饰后样品大倍率的放电比容量显著提升,1C下的容量由75 mAh·g^(-1)增加到115 mAh·g^(-1),Ag-TiO_2-MnO_2样品Mn-O键能的增强对于抑制放电过程中体积膨胀也有一定作用,可以使二氧化锰材料保持较好的结构稳定性.

The silver-titanium dioxide co-modified manganese dioxide（Ag-TiO2-MnO2）cathode material was prepared through high temperature solid state reaction.The microstructure,phase composition and electrochemical performance of the prepared samples were characterized by X-ray diffraction spectroscopy（XRD）,scanning electron microscopy（SEM）,Fourier transform infrared spectrometry（FT-IR）,X-ray photoelectron spectroscopy（XPS）,Energy-dispersive X-ray spectroscopy（EDS）,Cyclic voltammetry（CV）,galvanostatic discharge and electrochemical impedance spectroscopy（EIS）.Results showed that the unmodified and Ag-TiO2 modified MnO2 samples both exhibitedβ-MnO2 structurebut with different morphologies.The EDS mapping results revealed that Ag was uniformly dispersed on the surface of manganese dioxide,while Ti was relatively non-uniform in the Ag-TiO2-MnO2 sample.The modified samples were effective in improving specific discharge capacities.The specific discharge capacity increased from75 mAh·g^-1to 115 mAh·g^-1at the rate of 1C.The stronger bond energy of Mn-O in the modified MnO2 could suppress the volume expansion during the discharge process,which can maintain the structural stability of the manganese dioxide material.